首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7356篇
  免费   1篇
耳鼻咽喉   48篇
儿科学   176篇
妇产科学   49篇
基础医学   2046篇
口腔科学   2篇
临床医学   79篇
内科学   1121篇
皮肤病学   85篇
神经病学   554篇
特种医学   168篇
外科学   594篇
综合类   2篇
预防医学   98篇
眼科学   54篇
药学   1944篇
中国医学   5篇
肿瘤学   332篇
  2014年   4篇
  2013年   8篇
  2012年   8篇
  2011年   11篇
  2010年   10篇
  2009年   22篇
  2008年   39篇
  2007年   72篇
  2006年   156篇
  2005年   635篇
  2004年   789篇
  2003年   456篇
  2002年   138篇
  2001年   165篇
  2000年   148篇
  1999年   179篇
  1998年   100篇
  1997年   113篇
  1996年   235篇
  1995年   347篇
  1994年   312篇
  1993年   319篇
  1992年   267篇
  1991年   269篇
  1990年   201篇
  1989年   216篇
  1988年   196篇
  1987年   188篇
  1986年   170篇
  1985年   168篇
  1984年   154篇
  1983年   36篇
  1982年   146篇
  1981年   130篇
  1980年   126篇
  1979年   111篇
  1978年   110篇
  1977年   96篇
  1976年   110篇
  1975年   63篇
  1974年   70篇
  1973年   80篇
  1972年   71篇
  1971年   45篇
  1970年   18篇
  1969年   19篇
  1968年   22篇
  1967年   8篇
  1966年   1篇
排序方式: 共有7357条查询结果,搜索用时 15 毫秒
91.
Zusammenfassung Die BKS und 12 Plasmaproteine von 21 Kranken mit unterschiedlichen Krankheiten wurden statistisch miteinander verglichen. Dabei ergaben sich positive Korrelationen zwischen der BKS und dem sauren gif" alt="agr" align="BASELINE" BORDER="0">1-Glykoprotein und der BKS und dem gif" alt="agr" align="BASELINE" BORDER="0">1-Antitrypsin, eine negative Korrelation zwischen der BKS und dem Transferrin. Außerdem korrelierten das saure gif" alt="agr" align="BASELINE" BORDER="0">1-Glykoprotein und das gif" alt="agr" align="BASELINE" BORDER="0">1-Antitrypsin sowie das saure gif" alt="agr" align="BASELINE" BORDER="0">1-Glykoprotein und das Transferrin miteinander. Bei der Deutung dieser Ergebnisse müssen einerseits Gemeinsamkeitskorrelationen in Betracht gezogen werden, zum anderen die Möglichkeit, daß zwischen bestimmten Proteinmustern und der BKS Zusammenhänge bestehen.  相似文献   
92.
In the past 5 years enormous progress have been made in our understanding of the molecular basis for a number of inherited skin diseases characterized by easy blistering of the skin and the mucous membranes after minor physical trauma. This increased fragility of the skin or its appendages is due to molecular defects in genes coding for different intra- and extracellular structural proteins which are responsible for mechanical strength at their sites of expression. These diseases encompass the group of epidermolysis bullosa and disorders of cornification such as bullous forms of ichthyosis, palmoplantar keratoderma, and pachyonychia congenita. On the basis of clinical, morphological, and ultrastructural observations the epidermolysis bullosa group has been divided into three major categories. In epidermolysis bullosa simplex blister formation appears within the basal cell layer of the epidermis, and many mutations have been found in the genes of keratin 5 and 14 which are both expressed in basal keratinocytes. Epidermolytic hyperkeratosis leads to an epidermal separation in the suprabasal cell layers. In these patients numerous point mutations have now been described in the suprabasally expressed genes of keratin 1 and 10. In ichthyosis bullosa of Siemens blisters occur in the more upper suprabasal epidermis coincidental with the expression of keratin 2e, and mutations have been detected in the corresponding gene. In epidermolytic palmoplantar hyperkeratosis the suprabasal epidermal splitting is restricted to palms and soles of the patient. In keratin 9, which reveals such an exclusive expression pattern, molecular defects have indeed been recognized. Most recently in two different clinical subtypes of pachyonychia congenita, which is characterized by defective nails and focal palmoplantar hyperkeratosis, point mutations have been found in the genes coding for keratins 6, 16, and 17. In junctional epidermolysis bullosa the separation takes place within the dermal-epidermal basement membrane at the level of the lamina lucida, and mutations have been found in three genes coding for different laminin chains, in the gif" alt="beta" align="MIDDLE" BORDER="0">4 gene of gif" alt="agr" align="BASELINE" BORDER="0">6gif" alt="beta" align="MIDDLE" BORDER="0">4 integrin, and in the gene of collagen XVII. In dystrophic epidermolysis bullosa the tissue separation occurs beneath the basement membrane within the papillary dermis at the level of the anchoring fibrils, and several mutations have been identified in the collagen VII gene. The rapid unraveling of molecular defects in these disabling or even lethal inherited skin diseases makes possible a more precise and earlier prenatal diagnosis, creates new options for suitable therapeutic regimens, and even offers the hope of curing these diseases by means of somatic cell gene therapy.Abbreviations BM Basement membrane - BPAg Bullous pemphigoid antigen - DEB Dystrophic epidermolysis bullosa - EB Epidermolysis bullosa - EBS Epidermolysis bullosa simplex - EHK Epidermolytic hyperkeratosis - EPPK Epidermolytic palmoplantar keratoderma - IBS Ichthyosis bullosa of Siemens - JEB Junctional epidermolysis bullosa - KIF Keratin intermediate filaments - NC Noncollagenous domain - NEPPK Nonepidermolytic palmoplantar keratoderma - PC Pachyonychia congenita  相似文献   
93.
Summary The effects of beta-adrenergic agonists such as isoproterenol, norepinephrine and epinephrine upon the adenylate cyclase activity of human fat cell ghosts were tested, each alone and in combination with the beta-blocking agent propranolol. Saturating concentrations of these agents showed a 2–6.5-fold increase of enzyme activity without addition of any artificial cofactors. Isoproterenol was more potent in stimulating the enzyme system than epinephrine and nor-epinephrine. Propranolol caused a dose-dependent rightward shift of the log-dose response curve of these beta-adrenergic agonists. The assay of human fat cell adenylate cyclase in vitro may provide a simple and convenient assay system for the screening of beta-adrenergic drugs of potential therapeutic importance.Herrn Prof. Dr. Dr. h.c. G. Schettler zum 60. Geburtstag gewidmet  相似文献   
94.
The TGF-gif" alt="beta" align="MIDDLE" BORDER="0">1(–/–) mouse is a murine model for systemic autoimmune disease. The aim of this study is to elucidate the immunological mechanism that leads to multifocal tissue inflammation and autoantibody production in TGF-gif" alt="beta" align="MIDDLE" BORDER="0">1(–/–) mice. Heart, lung, liver, and salivary gland from TGF-gif" alt="beta" align="MIDDLE" BORDER="0">1(–/–) were assessed for CD154 expression by RT-PCR and immunohistochemistry. Compared to wild-type littermates, CD154 expression was elevated in all tissues studied. Furthermore, IL-12 mRNA was expressed in the salivary gland and heart of TGF-gif" alt="beta" align="MIDDLE" BORDER="0">1(–/–) mice and not in wild-type littermates. This suggests that the CD154 pathway is activated in these tissues. This shows that TGF-gif" alt="beta" align="MIDDLE" BORDER="0">1 regulates CD154 expression leading to spontaneous IL-12 production and autoimmunity.  相似文献   
95.
Lysle DT  Carrigan KA 《Inflammation》2001,25(4):267-275
The immunomodulatory effects of morphine are well established; however, suprisingly little is known about the immunomodulatory properties of the major metabolites of morphine. The present study tests the hypothesis that expression of inducible nitric oxide synthase (iNOS) is modulated by the administration of the morphine metabolite, morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide. The initial study using rats shows that morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide administration (0, 1.0, 3.163, 10 mg/kg s.c.) results in a pronounced reduction in lipopolysaccharide (LPS)-induced expression of iNOS (inducible nitricoxide synthease) in spleen, lung, and liver tissue as measured by western blotting. Morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide also produces a reduction in the level of plasma nitrite/nitrate, the more stable end-product of nitric oxide degradation. In a subsequent study, administration of the opioid receptor antagonist, naltrexone (0.1 mg/kg) prior to the injection of morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide (10 mg/kg) blocks the morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide induced reduction of iNOS expression and plasma nitrite/nitrite levels indicating that the effect is mediated via the opioid-receptor. This study provides the first evidence that morphine-6gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronide alters the expression of iNOS.  相似文献   
96.
Filtered glutathione (gif" alt="gamma" align="MIDDLE" BORDER="0">-glutamyl-cysteinyl-glycine or GSH) is rapidly hydrolyzed by brush-border enzymes facing the tubular lumen and is reabsorbed in the form of the constituent amino acids. The first step of hydrolysis is catalyzed by gif" alt="gamma" align="MIDDLE" BORDER="0">-glutamyltransferase (gif" alt="gamma" align="MIDDLE" BORDER="0">-GT). We investigated localization and capacity of the rat renal glutathione degradation/reabsorption during elevation of the filtered load (intravenous infusion of 12 resp. 18 gif" alt="mgr" align="MIDDLE" BORDER="0">mol GSH/min). Fractional excretion went up from about 0.003 to 0.31±0.02 SEM during infusion of the lower and to 0.49±0.03 SEM during infusion of the higher glutathione dose. GSH degradation/reabsorption took place along the entire proximal tubule and was partially saturated by a 150–200-fold elevation of the normal filtered load. Net reabsorption of GSH up to the last accessible superficial loop was significantly lower during infusion of 18 gif" alt="mgr" align="MIDDLE" BORDER="0">mol GSH/min (0.3 gif" alt="mgr" align="MIDDLE" BORDER="0">mol/min) than during infusion of 12 gif" alt="mgr" align="MIDDLE" BORDER="0">mol GSH/min (1.6 gif" alt="mgr" align="MIDDLE" BORDER="0">mol/min). In further experiments, infusion of 18 gif" alt="mgr" align="MIDDLE" BORDER="0">mol GSH/min was preceded by the i.v. administration of acivicin (0.5 mmol/kg body wt.), an inhibitor of gif" alt="gamma" align="MIDDLE" BORDER="0">-GT. In these experiments, fractional glutathione deliveries to late proximal and early distal tubules did not significantly differ from 1, fractional excretion of GSH at the same time was 1.46±0.11 SEM, revealing net secretion of GSH with the final urine. Tubular secretion of GSH in the acivicin-treated animals occurred either in distal tubules and/or collecting ducts or in the proximal tubules of deep nephrons which are not accessible to micropuncture. The low net reabsorption of GSH up to the late proximal tubule during infusion of 18 gif" alt="mgr" align="MIDDLE" BORDER="0">mol GSH/min without prior administration of acivicin indicates tubular secretion of GSH along the proximal convolution of superficial nephrons. Net secretion of glutathione with the final urine in the acivicin-treated animals therefore probably originates from proximal tubules of deep nephrons.Supported by the gif" alt="ldquo" align="MIDDLE" BORDER="0">Wilhelm-Sander-Stiftunggif" alt="rdquo" align="MIDDLE" BORDER="0">. Parts of this work were presented at the 4th International Workshop on Ammoniagenesis, Cadarache, France, August 1987, and at the 65th meeting of the Deutsche Physiologische Gesellschaft, Würzburg, March 1988 (Pflügers Arch 411:R97)  相似文献   
97.
98.
We previously demonstrated the activity of the R fragment in the long terminal repeat of human T-cell leukemia virus type I for elevation of the level of gene expression. In this study, the fragment was deleted with BAL31 nuclease to determine its functional domain. Series of the shortened R fragments were linked to the simian virus 40 promoter unit, which regulated expression of a reporter gene. Examination with the R fragments deleted from the 5gif" alt="prime" align="BASELINE" BORDER="0"> and 3gif" alt="prime" align="BASELINE" BORDER="0"> ends showed that borders of the functional domain were mapped within nucleotide positions 458 to 473 for the 5gif" alt="prime" align="BASELINE" BORDER="0"> end and nucleotide positions 559 to 594 for the 3gif" alt="prime" align="BASELINE" BORDER="0"> end, respectively. Thus we conclude that a 136-base-pair fragment corresponding to the second half of the R region was sufficient to allow elevation of the level of gene expression.  相似文献   
99.
Using whole-cell patch-clamp techniques we found that ATP activated an outwardly rectifying current in Daudi human B lymphoma cells under acidic conditions. The substitution of Cl for gluconate shifted the reversal potential, while Cl channel blockers, 4,4gif" alt="rsquo" align="BASELINE" BORDER="0">-diisothiocyanostibene-2,2gif" alt="rsquo" align="BASELINE" BORDER="0">-disulfonic acid (DIDS) and 9-anthracene carboxylic acid (9-AC), blocked the current, indicating that ATP induces this current by activating the outwardly rectifying chloride channel (ORCC). The effect of ATP on ORCC was mimicked by ADP, but not by other P2 receptor agonists such as ATPgif" alt="gamma" align="MIDDLE" BORDER="0">S (a poorly hydrolyzable analog of ATP), 2gif" alt="rsquo" align="BASELINE" BORDER="0">,3gif" alt="rsquo" align="BASELINE" BORDER="0">-O-benzoyl-4-benzoyl-ATP (BzATP), and UTP. The ATP-induced ORCC current was completely blocked by 100 gif" alt="mgr" align="MIDDLE" BORDER="0">M suramin (a P2 receptor antagonist), and was partially blocked by 100 gif" alt="mgr" align="MIDDLE" BORDER="0">M pyridoxal-phosphate-6-azophenyl-2gif" alt="rsquo" align="BASELINE" BORDER="0">,4gif" alt="rsquo" align="BASELINE" BORDER="0">-disulfonic acid tetrasodium (PPADS), which is another P2 receptor antagonist. Neither inactivation of G proteins nor elimination of extracellular Ca2+ affected the ATP-induced current, indicating that G protein-coupled P2Y receptors and Ca2+-permeable P2X receptors are not involved. Based on the pharmacological profile and the fact that acidic conditions are required for ATP to activate the ORCC, we suggest that acidic ATP activates the lymphocyte ORCC via a novel pathway, which is not associated with any previously described purinergic receptors.  相似文献   
100.
Adrenaline infusion of 0.1 gif" alt="mgr" align="MIDDLE" BORDER="0">g · kg–1 · min–1 in healthy volunteers results in an increase of hepatic glucose production, an increase of the absolute number of occupied gif" alt="beta" align="MIDDLE" BORDER="0">-adrenoceptors and specific changes in metabolism. To compare these effects with the changes induced by an endogenous catecholamine release, we investigated healthy volunteers during cycle ergometry. After fasting at least 14 h seven healthy subjects exercised for 90 min at an intensity of 20% below their individual anaerobic threshold. The rate of glucose production as well as the turnover rates of alanine and leucine were calculated using stable isotope tracers. High and low affinity gif" alt="beta" align="MIDDLE" BORDER="0">-adrenergic binding sites on lymphocytes were determined by an equilibrium binding assay with (–)125 Iodocyanopindolol. After 90 min of cycling the rate of appearance of glucose increased significantly from means of 2.0 (SD 0.2) to 2.65 (SD 0.50) mg · kg–1 · min–1 with unchanged blood concentrations of glucose and lactate. The flux of the amino acids alanine and leucine decreased significantly from means of 0.91 (SD 0.21) to 0.62 (SD 0.14) mg · kg–1 · min–1 and from 0.40 (SD 0.05) to 0.32(SD 0.04) mg · kg–1 · min–1, respectively. The mean free fatty acid concentration increased significantly from 0.65 (SD 0.33) to 1.27 (SD 0.45) mmol · l–1 during the endurance trial. The increase of glucose turnover and the decrease of amino acid flux point to a metabolic shift towards enhanced utilization of free fatty acids. Adrenaline and noradrenaline concentrations showed a moderate but significant increase from means of 0.61 (SD 0.20) to 0.99 (SD 0.36) nmol · l–1 and from 2.27 (SD 0.75) to 3.46 (SD 0.38) nmol · 1–1, respectively. The number of high affinity gif" alt="beta" align="MIDDLE" BORDER="0">-adrenergic binding sites per cell (gif" alt="beta" align="MIDDLE" BORDER="0">-adrenoceptors) nearly doubled from 770 (SD 130) to 1490 (SD 150) during 90 min of cycling. The observed endogenous plasma catecholamine concentrations were not sufficient to change significantly the relative receptor occupancy. This would seem to indicate that the aerobic exercise induced effects depended more on the absolute number of occupied gif" alt="beta" align="MIDDLE" BORDER="0">-adrenoceptors than on their relative receptor occupancy. When compared to the results of the adrenaline infusion experiment the increases of the hepatic glucose production and the increase of gif" alt="beta" align="MIDDLE" BORDER="0">-adrenoceptors were very similar in both groups despite ten times higher adrenaline plasma concentrations in the infusion group. This would seem to indicate that gif" alt="beta" align="MIDDLE" BORDER="0">-adrenoceptors mediated effects do not correlate with catecholamine plasma concentrations.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号