全文获取类型
收费全文 | 7477篇 |
免费 | 326篇 |
国内免费 | 111篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 125篇 |
妇产科学 | 63篇 |
基础医学 | 1223篇 |
口腔科学 | 152篇 |
临床医学 | 331篇 |
内科学 | 978篇 |
皮肤病学 | 92篇 |
神经病学 | 832篇 |
特种医学 | 271篇 |
外科学 | 869篇 |
综合类 | 435篇 |
预防医学 | 1103篇 |
眼科学 | 59篇 |
药学 | 980篇 |
中国医学 | 98篇 |
肿瘤学 | 279篇 |
出版年
2023年 | 296篇 |
2022年 | 458篇 |
2021年 | 516篇 |
2020年 | 603篇 |
2019年 | 398篇 |
2018年 | 312篇 |
2017年 | 249篇 |
2016年 | 170篇 |
2015年 | 150篇 |
2014年 | 334篇 |
2013年 | 315篇 |
2012年 | 192篇 |
2011年 | 259篇 |
2010年 | 220篇 |
2009年 | 208篇 |
2008年 | 179篇 |
2007年 | 199篇 |
2006年 | 215篇 |
2005年 | 213篇 |
2004年 | 191篇 |
2003年 | 182篇 |
2002年 | 111篇 |
2001年 | 106篇 |
2000年 | 86篇 |
1999年 | 90篇 |
1998年 | 69篇 |
1997年 | 74篇 |
1996年 | 101篇 |
1995年 | 87篇 |
1994年 | 93篇 |
1993年 | 108篇 |
1992年 | 71篇 |
1991年 | 79篇 |
1990年 | 63篇 |
1989年 | 52篇 |
1988年 | 49篇 |
1987年 | 45篇 |
1986年 | 52篇 |
1985年 | 81篇 |
1984年 | 116篇 |
1983年 | 72篇 |
1982年 | 89篇 |
1981年 | 62篇 |
1980年 | 47篇 |
1979年 | 49篇 |
1978年 | 45篇 |
1977年 | 35篇 |
1976年 | 33篇 |
1975年 | 20篇 |
1974年 | 18篇 |
排序方式: 共有7914条查询结果,搜索用时 0 毫秒
71.
Florry A. Vyth-Dreese Trees A. M. Dellemijn Donn Majoor Daphne de Jong 《European journal of immunology》1995,25(11):3023-3029
Functional interactions between B and T lymphocytes are known to depend on the expression of co-stimulatory molecules B7.1/CD80, B7.2/CD86 and their counter-receptors CD28 and CTLA4, as well as CD40 and its ligand CD40L. To study the role of these molecules in situ, an immunohistochemical analysis was carried out on normal human lymphoid tissue. In the germinal centers (GC), B7.1 and B7.2 were differentially expressed. In the dark zone, centroblasts were predominantly B7.1+, while centrocytes in the light zone were B7-2+, resulting in reversed gradients of both markers in GC. Follicle mantle cells were negative for B7.1 and B7.2. Macrophages and interdigitating dendritic cells (IDC) in T cell zones both expressed B7.1 and B7.2. Moreover, clusters of B7.2+ T cells were demonstrated in interfollicular areas. Intrafollicular CD4+ T cells in GC, predominantly in the apical light zone, expressed CD28 and CTLA4, as did the majority of interfollicular T cells. CTLA4 showed a striking excentric cytoplasmic staining, which was also seen on T cells activated in vitro. CD40 was expressed on all B cells and more strongly on macrophages and IDC. Moreover, small clusters of T cells in a rim outside the GC showed CD40 expression. CD40L was expressed both on intrafollicular CD4+ T cells as well as on T cells in T cell zones. The differential distribution of co-stimulatory molecules in different compartments of normal human lymphoid tissue in situ indicates that these interactions play a distinctive role in different stages of B cell differentiation and in the immune response. 相似文献
72.
G. Ya. Pervukhin I. N. Sharonova S. E. Prokof'ev N. B. Fedorov V. B. Sokolov I. V. Martynov 《Bulletin of experimental biology and medicine》1991,111(4):425-427
Laboratory of Organic Synthesis, Reception of Physiologically Active Substances Group, Institute of Physiologically Active Substances, Academy of Sciences of the USSR, Chernogolovka, Moscow Region. Laboratory of Functional Synaptology, Brain Institute, All-Union Mental Health Research Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR O. S. Adrianov. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 4, pp. 339–341, April, 1991. 相似文献
73.
Norio Yoshimura Takahiro Oka Masakazu Kita Hiroshi Teraoka Yoshikatsu Hirai 《Journal of clinical immunology》1989,9(4):322-328
The present study examined the effect of cyclosporine (CsA) administered with steroidin vivo on the capacity of peripheral blood mononuclear cells (PBMC) from kidney transplant recipients to generate cytokines and their gene expression at the level of messenger RNA (mRNA). PBMC from CsA-prednisolone (Pred)-treated recipients displayed 66.9% inhibition (54.3±12.4 IU/ml;N=42;P<0.01) of -interferon (-IFN) production compared with normal individuals (134.6±18.6 IU/ml;N=23). Azathioprine (Az)-Pred-treated recipients displayed significantly less inhibition of -IFN generation (96.0±16.1 IU/ml;N=22;P<0.05) than CsA-treated patients. Macrophages (m) from CsA-Pred-treated recipients displayed 60.0% inhibition (5.1±0.7 U/ml;N=20;P<0.01) of interleukin-1 (IL-1) production compared with normal individuals (13.0±2.9 U/ml;N=21). These results were confirmed by the experiments using cDNA probe for -IFN or IL-1 (, ). High levels of -IFN mRNA in phytohemagglutinin (PHA)-stimulated PBMC or IL-1() mRNA in lipopolysaccharide (LPS)-stimulated m were present in normal individuals but not in CsA-treated recipients as judged by hybridization to a cloned human -IFN or IL-1() cDNA probe. These studies demonstrated that combination therapy of CsA with steroid inhibits both -IFN and IL-1 gene expression at the level of mRNA at physiological concentrations. 相似文献
74.
Eric N. Juberg Kenneth P. Minneman Peter W. Abel 《Naunyn-Schmiedeberg's archives of pharmacology》1985,330(3):193-202
Summary The properties of
1- and
2-adrenoceptors in right and left atria of rat heart, and their roles in mediating chronotropic and inotropic responses to-adrenoceptor agonists were examined. [125I](-)-pindolol (125IPIN) bound saturably and specifically to a single class of high affinity sites in homogenates of both right and left atria. Thek
1's for association in right and left atria were 6.5×109 l/mol-min and 2.3×109 l/mol-min respectively, while thek
–1's for dissociation were 0.20 min–1 and 0.17 min–1. The kinetically determinedK
D's were 75 pmol/l in right and 30 pmol/l in left atria and were similar to the equilibriumK
D's determined from Scatchard analysis of saturation isotherms of specific125IPIN binding. Inhibition of125IPIN binding by-adrenoceptor antagonists was stereoselective and the order of potency was timolol > 1-propranolol > d-propranolol > sotalol. Inhibition by
1- and
2-adrenoceptor subtype selective antagonists yielded flat displacement curves with low Hill coefficients. Nonlinear regression analysis of displacement by
1-selective (practolol, atenolol and metoprolol) and
2-selective (ICI 118,551) antagonists gave estimates of the proportion of
1- and
2-adrenoceptors present in rat atria. Right atria contained 67±4.2%
2-adrenoceptors and 33±4.2%
2-adrenoceptor, while left atria contained 67±2.8%
1- and 33±2.8%
2-adrenoceptors. Increases in the rate of spontaneously beating right atria and the force of electrically driven left atria caused by-adrenoceptor agonists were also measured. pA2 values for non-subtype selective-adrenoceptor antagonists in inhibiting isoprenaline-induced increases in rate and force were highly correlated withK
D values determined for specific125IPIN binding. pA2 values for
1- and
2-selective antagonists in inhibiting isoprenaline-induced increases in rate and force correlated well with the pK
D values of these drugs in binding to
1-adrenoceptors, but not with the pK
D values in binding to
2-adrenoceptors. Dose-response curves for stimulation of both rate and force by the
2-selective agonists procaterol and zinterol were shifted to a much greater extent by selective blockade of
1-adrenoceptors with metoprolol than by selective blockade of
2-adrenoceptors with ICI 118,551, suggesting that these compounds caused their effects by activating
1-adrenoceptors. These results suggest that
1- and
2-adrenoceptors coexist in both left and right atria of rat heart in approximately a 21 ratio, however only
1-adrenoceptors mediate the chronotropic and inotropic effects of-adrenoceptor agonists.Supported by a grant from the American Heart Association — Georgia Affiliate 相似文献
75.
W. Schaupp H. -W. Menges und M. Trede 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1987,372(1):839
Zusammenfassung In einer randomisierten Studie wurden 200 Patienten in 2 Gruppen eingeteilt: Konventionelle Cholecystektomie (CE): Magensonde, Drainage und postop. Infusionsbehandlung; ideale CE: keine Drainage, keine Magensonde, keine postop. Infusionsbehandlung. Es gab keine signifikanten Unterschiede bezüglich Schmerzmittelbedarf, OP-Zeit, postop. Aufenthaltsdauer und Fieber-Tage, Beginn der Darmtätigkeit und postop. Komplikationsrate. 2 Komplikationen wurden hervorgehoben: In der 1. Gruppe kam es zu einem subhepatischen Abscess, in der 2. zu einer Gallefistel. Schlufolgerung: Unsere ideale CE: Keine Magensonde, keine Infusionsbehandlung, aber eine subhepatische Drainage. 相似文献
76.
Hairy cell leukemia (HCL) is a rare chronic lymphoproliferative disorder which has been extensively studied over the past decade. Much has been learned regarding the diagnosis, natural history, biology, and treatment of this unique neoplasm. The disease most commonly affects middle aged men and characteristic clinical features include splenomegaly, cytopenias, and usually the presence in the peripheral blood of distinctive thairy cells with irregular cytoplasmic projections. Diagnosis can usually be confirmed by bone marrow biopsy. Although the natural history can be extremely variable among patients, complications are usually referable to the cytopenias, with anemia and infection being most frequent. In addition to pyogenic infections, patients are susceptible to unusual organisms including atypical mycobacterium, legionella, and fungi. The requirement of red blood cell transfusion, severe granulocytopenia or thrombocytopenia, frequent infections, or painful splenomegaly are all indications for treatment. Splenectomy is the standard initial treatment of choice. However, in the past few years there have been exciting major advances in the therapeutic modalities for HCL. Recombinant alfa-interferon is highly effective, with beneficial responses occurring in close to 90% of patients. The Food and Drug Administration has recently approved the use the interferon for HCL. This represents the first time a biological response modifier has been approved for the treatment of human disease. In addition, preliminary results with the adenosine deaminase inhibitor, 2 deoxycoformycin (def), have been encouraging. Further clinical trials are required in order to determine the optimal sequential treatment strategy for HCL. The exact mechanisms of action of both interferon and def in HCL remain to be elucidated. A better understanding of the unusual features of the hairy cell and the underlying biological effect of these two agents in HCL may have important applications in other hamatologic and non-hematologic malignancies. 相似文献
77.
Summary Patients with malignant disease may be predisposed to bacterial infections because of neoplastic disruption of normal tissue barriers, exogenous immunosuppressive therapy (drugs with or without radiation), and intrinsic host immune deficits secondary to these diseases. Diminished polymorphonuclear leukocyte numbers or function and impaired humoral immunity are highly correlated with the development of serious bacterial infections. The usual signs and symptoms of infection may be absent or altered in a compromised host.Therapy must be instituted promptly upon clinical suspicion of bacterial infection, and empirical choices should usually include combinations that are synergistic for likely pathogens based on knowledge of the local predominant flora and susceptibility data. Synergism has most often been demonstrated in combinations that utilize a -lactam (semisynthetic penicillin or cephalosporin) and an aminoglycoside. Triple drug therapy has not been shown to be advantageous. Monotherapy with third generation cephalosporins, carbapenems, monobactams, or ureidopenicillins has not been proven to offer advantages over 2-drug regimens for these patients.Patients with blood deficient in granulocytes (granulocytopenic) who respond to 2-drug therapy but remain deficient in neutrophils (neutropenic) may need continued treatment until the neutropenia subsides. Those who do not respond and remain febrile with an unclear focus of infection may need to be started on antifungal therapy in addition to the antibacterial agent. The use of oral agents for the prophylaxis of neutropenic patients against bacteremia remains controversial. If drugs are used, co-trimoxazole and nystatin suspension may be preferable. 相似文献
78.
W. L. E. M. Hesp E. J. C. Lubbers H. H. M. de Boer Th. Hendriks 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1986,368(2):105-111
Summary In the period 1977–1981 234 small bowel anastomoses were constructed in 143 patients. Eight anastomoses showed leakage (3.4%) and from nine anastomoses a fistula developed (3.8%): a total rate of disturbed healing of small bowel anastomoses (7.3%). In the presence of intra-abdominal infection this rate was 14.8%, in the absence of infection 0.8%. The results of treatment with oversewing and with resection and immediate anastomosis were disappointing. Better results were obtained by dismantling of the anastomosis, establishment of a split-enterostomy and reestablishment of continuity in a second stage. Mortality was 3/17 (18%). The literature is reviewed.
Insuffizienz von Dünndarmanastomosen — Ineidenz und Therapie
Zusammenfassung In dem Zeitraum 1977–1981 wurden bei 143 Patienten 234 Dünndarmanastomosen angelegt. Acht Anastomosen zeigten eine Nahtleckage (3,4%), bei neun entwickelte sich eine Fistel (3,8%): die Gesamthäufigkeit von Wundheilungsstörungen bei Dünndarmanastomosen war 7,3%. Bei gleichzeitigem Vorliegen intraabdominaler Infektionen betrug die Häufigkeit 14,8%, ohne diese 0,8%. Die Resultate einer Therapie durch Übernähung oder Resektion mit sofort anschließender Reanastomosierung waren enttäuschend. Befriedigendere Ergebnisse wurden durch Aufheben der Anastomosen, Anlage einer split enterostomy unter Wiederherstellung der Kontinuität in einer zweiten Sitzung erzielt. Die Mortalität betrug 3/17 (18%). Ein Literaturüberblick wird gegeben.相似文献
79.
ZK 91296, a partial agonist at benzodiazepine receptors 总被引:2,自引:0,他引:2
Petersen Erling N. Jensen Leif H. Honoré Tage Braestrup Claus Kehr Wolfgang Stephens David N. Wachtel Helmuth Seidelman Dieter Schmiechen Ralph 《Psychopharmacology》1984,83(3):240-248
ZK 91296 (ethyl 5-benzyloxy-4-methoxymethyl--carboline-3-carboxylate) is a potent and selective ligand for benzodiazepine (BZ) receptors. Biochemical investigations indicate that ZK 91296 may be a partial agonist at BZ receptors. Such partial agonism may explain to some extent why ZK 91296 needs higher BZ receptor occupancy than diazepam for the same effect against chemical convulsants and for behavioural effects. The lack of sedatiye effects, and the very potent inhibition of reflex epilepsy, spontaneous epilepsy and DMCM-induced seizures suggest, furthermore, that ZK 91296 may possess pharmacological selectivity for a particular type of BZ receptor interaction, perhaps including topographic as well as receptor subtype differentiation. 相似文献
80.
R. Bendayan J. A. Pieper R. B. Stewart G. J. Caranasos 《European journal of clinical pharmacology》1984,26(2):251-254
Summary The extent of propranolol protein binding was determined in three different age groups of healthy drug-free caucasian males. Volunteers selected for study were 6–15 years old, 25–36 years old and 68–76 years old. Ten milliliters of blood were obtained via venipuncture and collected in glass tubes from the subjects after an overnight fast. Binding determinations were performed by equilibrium dialysis using radiolabelled propranolol. Serum albumin and 1-acid glycoprotein concentrations were determined in all subjects by radial immunodiffusion. The results obtained showed wide intersubject variability in the binding ratio of propranolol and serum concentrations of 1-acid glycoprotein. Mean albumin serum concentration was found to be significantly lower in the elderly group as compared to the adult and pediatric groups (p<0.02). A positive correlation was found between the binding ratio of propranolol and the serum concentration of 1-acid glycoprotein in all the subjects (r=+0.66,p<0.005). No significant correlation was found between the binding ratio of propranolol and the serum concentration of albumin (r=–0.03,p<0.88). These data suggest that the extent of propranolol binding is influenced primarily by serum concentrations of 1-acid glycoprotein and not by differences in age. 相似文献