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   13199篇
  免费   934篇
  国内免费   48篇
耳鼻咽喉   124篇
儿科学   508篇
妇产科学   344篇
基础医学   1966篇
口腔科学   260篇
临床医学   1649篇
内科学   2596篇
皮肤病学   212篇
神经病学   1383篇
特种医学   297篇
外国民族医学   1篇
外科学   1205篇
综合类   72篇
一般理论   10篇
预防医学   1237篇
眼科学   214篇
药学   960篇
中国医学   17篇
肿瘤学   1126篇
  2023年   96篇
  2022年   139篇
  2021年   321篇
  2020年   249篇
  2019年   359篇
  2018年   394篇
  2017年   281篇
  2016年   358篇
  2015年   357篇
  2014年   488篇
  2013年   698篇
  2012年   995篇
  2011年   967篇
  2010年   527篇
  2009年   499篇
  2008年   932篇
  2007年   880篇
  2006年   808篇
  2005年   834篇
  2004年   744篇
  2003年   634篇
  2002年   612篇
  2001年   153篇
  2000年   106篇
  1999年   134篇
  1998年   145篇
  1997年   115篇
  1996年   87篇
  1995年   87篇
  1994年   79篇
  1993年   77篇
  1992年   61篇
  1991年   64篇
  1990年   65篇
  1989年   59篇
  1988年   46篇
  1987年   39篇
  1986年   44篇
  1985年   51篇
  1984年   51篇
  1983年   35篇
  1982年   32篇
  1981年   53篇
  1980年   32篇
  1979年   35篇
  1978年   29篇
  1976年   29篇
  1974年   21篇
  1972年   21篇
  1971年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Zusammenfassung 1.Beobachtungen aus der Gewichtskurve lassen einen klimatischen Einflu\ auf die Zunahme möglich erscheinen. 2. Der Hämoglobingehalt war nach dem Aufenthalt in 55% gesteigert; bei der Nachuntersuchung nach 6 Wochen zeigte sich in 47 % ein Erfolg gegenÜber dem Anfangswert. 3. Untersuchungen mit dem Ergographen ergaben eine Erhöhung der Muskelkraft und Verringerung der ErmÜdbarkeit. 4. Es fand eine gewisse Anpassung der Herztätigkeit au eine Arbeitsleistung statt. 5. Die Vitalkapazität hat in 47% zugenommen. 6. Die Reaktion der Vasomotoren auf Kältereiz war verkÜrzt.  相似文献   
102.
Circulating spontaneous antibody-secreting cells (ASC) induced by mucosal and systemic immunizations in human volunteers have been characterized with respect to differentiation stage and homing commitments. Irrespective of the immunization route, the large majority of ASC co-expressed CD19 and HLA-DR, which are normally lost during the transition of plasmablasts to plasmocytes, as well as CD38, a marker of activated B cell blasts, expressed also by plasmocytes. However, these cells expressed neither CD28, a molecule acquired by plasmocytes, nor CD22 and CD37, which are lost during the transition of plasmablasts to plasmocytes. Therefore, the large majority of ASC found in peripheral blood after oral and parenteral immunizations are terminally differentiated B cells, but not fully differentiated plasmocytes. As a whole, the mucosally derived ASC population seemed to be more homogenously differentiated. CD25 was detected on few ASC, whereas ASC expressing CD71 were more numerous, especially among systemically derived ASC. Almost all ASC expressed the adhesion molecules CD44 and α4-integrins, irrespective of immunization route. However, virtually all systemically derived ASC expressed L-selectin, recognizing the peripheral lymph node addressin, whereas only a minority of mucosally induced blood ASC expressed L-selectin. These studies are the first to demonstrate in humans that circulating precursors of mucosal B cell immunoblasts utilize organ-specific recognition mechanisms distinct from those of corresponding systemic B cells and appear to be more advanced in the B lineage maturation pathway. Specialization of receptor expression could explain both the unification of immune responses in diverse mucosal sites and the physiologic segregation of mucosal from non-mucosal immune mechanisms in humans.  相似文献   
103.
Complex reciprocal interactions between hepatitis C (HCV) and hepatitis B (HBV) viruses (HBV) have been reported. We examined the influence of HBV on HCV RNA titers in 376 HCV/HIV-coinfected patients (30 were also HBsAg positive). Regression analyses identified negative HBsAg and male sex as factors associated with HCV RNA values >500,000 IU/mL.  相似文献   
104.
Three new missense mutations (H15D, A83D, and A179D) and a new splicing defect (573 + 1G→A) in the 5′ splice site of intron 5 were among six mutant adenosine deaminase (ADA) alleles found in three unrelated patients with severe combined immunodeficiency disease, the most common phenotype associated with ADA deficiency. When expressed in vitro, the H15D, A83D, and A179D proteins lacked detectable ADA activity. The splicing defect caused skipping of exon 5, resulting in premature termination of translation and a reduced level of mRNA. H15D is the first naturally occurring mutation of a residue that coordinates directly with the enzyme-associated zinc ion. Molecular modeling based on the atomic coordinates of murine ADA suggests that the D15 mutation would create a cavity or gap between the zinc ion and the side chain carboxylate of D15. This could alter the ability of zinc to activate a water molecule postulated to play a role in the catalytic mechanism. A83 and A179 are not directly involved in the active site, but are conserved residues located respectively in a helix 4 and β strand 4 of the α/β barrel. Replacement of these small hydrophobic Ala residues with the charged, more bulky Asp side chain may distort ADA structure and affect enzyme stability or folding.© 1995 wiley-Liss, Inc.  相似文献   
105.
Nineteen patients that had developed hypertrophic scars subsequent to thermal injury were typed for HLA class II allogenotypes with the restriction fragment length polymorphism technique. A significant association was found with DR beta 16 (pc = 1.45 x 10(-4); relative risk = 12.25). This finding adds evidence to other data suggesting that immunologic phenomena are involved in pathologic scarring. Moreover, the results presented here have allowed an identification of a genetically determined risk factor for hypertrophic scar formation located in the HLA region.  相似文献   
106.
The aim of the present research was to study individual response specificity in 22 male patients having essential hypertension (HT) and to compare these patients with age-matched male normotensive controls (NT). Four stimuli, letter identification, mental arithmetic, cold pressor and isometric exercise, were administered while recordings were made of: systolic and diastolic blood pressures, heart rate, respiration, forearm and hand blood flows, and skin conductance level and fluctuations. After each session urine samples were collected and epinephrine and norepinephrine levels were analyzed. Twelve subjects in the HT group were given beta-adrenergic blocking agents and retested 1 to 21 months (X?= 12 months) after the first session. Each response was standardized, using NT as the reference group. Intraclass correlations were computed to evaluate whether HT males reacted with a more consistent hierarchy of responses than did NT. Intraclass correlations were significantly higher among the patients than in the control group, regardless of whether the blood pressure response was included or excluded in the computation of the intraclass correlations. Thus, we conclude that male HT patients show more individual response specificity than NT controls. Beta-adrenergic receptor antagonists reduced levels of cardiovascular activity and attenuated reactivity but did not affect amount of specificity. Thus, intraclass correlations provide unique and useful information, since they are not related to blood pressure reactivity or to urinary catecholamine levels, nor affected by beta-adrenergic blockade.  相似文献   
107.
Occurrence of renal involvement in Rheumatoid arthritis is uncommon; when present it has been attributed to amyloid or secondary effects of drugs. Nevertheless, recent observations seem to indicate the existence of primary renal lesions associated with the disease. The purpose of this paper is to review the data suggesting that the kidney can be directly involved in Rheumatoid arthritis. The main points of interest are the occurrence of glomerulonephritis and/or amyloidosis, the presence of vasculitis and other arterial changes, the existence of chronic interstitial nephritis and papillary necrosis and lesions associated with gold and penicillamine therapy.  相似文献   
108.
Recent results obtained using molecular biology techniques have suggested a possible role for insulin-like growth factor II (IGF-II) in the pathogenesis of hepatocellular carcinoma (HCC). To investigate this phenomenon, a monoclonal anti-body was used against IGF-II to study 54 patients with HCC. The presence of HBsAg was also tested both in serum and liver tissue. A positive immunoreaction was found in 9/15 (60%) of the HCC arising in cirrhotic livers of patients who had serum markers for HBV (HBV+ positive patients). These results provide further evidence that HBV might play a role in the expression of IGF-II. In HCC of patients without any markers of HBV infection (HBV- negative patients), IGF–II was detected in 10/39 (25.6%) of the tumors, and in some benign neoplastic lesions. It was found not only in neoplastic cells but also in some dysplastic nodules. The speculation arises that IGF–II expression may play a role in some steps of hepato-carcinogenesis.  相似文献   
109.
Evidence that gamma/delta T cells play a broad, immunoregulatory role has been accumulating steadily. We show here that myeloid cells are disregulated after peritoneal infection with Listeria monocytogenes in mice lacking gamma/delta T cells. Inflammatory populations of neutrophils and monocytes recruited to the site of infection remained longer. Intracellular cytokine analysis showed that frequencies of myeloid cells producing interleukin-12 and tumor necrosis factor alpha were higher and remained elevated longer after infection in mice genetically deficient in gamma/delta T cells. In vivo dye-tracking studies indicated that the majority of inflammatory monocytes differentiated into resident tissue macrophages in situ. In vitro experiments confirmed that monocytes harvested from mice lacking gamma/delta T cells were defective in their maturation process. This evidence suggests that gamma/delta T cells promote differentiation in the monocyte/macrophage lineage. These cells are important for bactericidal activity, inflammatory cytokine production, clearance of inflammatory neutrophils, and ultimately, antigen presentation to T cells. Regulation of monocyte/macrophage differentiation may underlie a broad segment of the phenotypic alterations that have been reported in mice lacking gamma/delta T cells.  相似文献   
110.
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