全文获取类型
收费全文 | 8899篇 |
免费 | 764篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 227篇 |
儿科学 | 324篇 |
妇产科学 | 227篇 |
基础医学 | 1087篇 |
口腔科学 | 227篇 |
临床医学 | 996篇 |
内科学 | 1814篇 |
皮肤病学 | 243篇 |
神经病学 | 659篇 |
特种医学 | 502篇 |
外科学 | 1519篇 |
综合类 | 172篇 |
一般理论 | 8篇 |
预防医学 | 676篇 |
眼科学 | 150篇 |
药学 | 346篇 |
中国医学 | 2篇 |
肿瘤学 | 519篇 |
出版年
2021年 | 91篇 |
2019年 | 84篇 |
2018年 | 108篇 |
2017年 | 91篇 |
2016年 | 88篇 |
2015年 | 120篇 |
2014年 | 144篇 |
2013年 | 244篇 |
2012年 | 295篇 |
2011年 | 308篇 |
2010年 | 206篇 |
2009年 | 189篇 |
2008年 | 276篇 |
2007年 | 345篇 |
2006年 | 341篇 |
2005年 | 343篇 |
2004年 | 304篇 |
2003年 | 339篇 |
2002年 | 318篇 |
2001年 | 267篇 |
2000年 | 291篇 |
1999年 | 259篇 |
1998年 | 104篇 |
1997年 | 105篇 |
1996年 | 111篇 |
1995年 | 105篇 |
1994年 | 94篇 |
1993年 | 97篇 |
1992年 | 242篇 |
1991年 | 242篇 |
1990年 | 228篇 |
1989年 | 260篇 |
1988年 | 214篇 |
1987年 | 220篇 |
1986年 | 221篇 |
1985年 | 206篇 |
1984年 | 178篇 |
1983年 | 124篇 |
1982年 | 100篇 |
1981年 | 85篇 |
1979年 | 143篇 |
1978年 | 110篇 |
1976年 | 85篇 |
1975年 | 83篇 |
1974年 | 96篇 |
1973年 | 150篇 |
1972年 | 87篇 |
1971年 | 101篇 |
1970年 | 107篇 |
1969年 | 97篇 |
排序方式: 共有9698条查询结果,搜索用时 15 毫秒
11.
12.
R. Christopher Pierce Amy J. Clemens Laura A. Shapiro George V. Rebec 《Psychopharmacology》1994,116(1):103-109
Acute administration of neuroleptic drugs alters the extracellular level of ascorbate in the neostriatum, and increasing evidence suggests a role for this vitamin in the behavioral, and possibly therapeutic, effects of these drugs. To shed further light on this issue, extracellular ascorbate was recorded in the neostriatum and nucleus accumbens of awake, behaving rats following chronic treatment with either classical (haloperidol) or atypical (clozapine) neuroleptics or ascorbate itself. Electrochemically modified, carbon-fiber microelectrodes were lowered in place the day after the last of 21 daily injections of either haloperidol (0.5 mg/kg, SC), clozapine (20 mg/kg, IP), sodium ascorbate (500 mg/kg, IP) or vehicle. Voltammetric measurements were obtained during quiet rest and following administration ofd-amphetamine (2.5 mg/kg). Repeated treatment with either haloperidol or ascorbate elevated basal extracellular ascorbate and potentiated the amphetamine-induced increase in ascorbate release in neostriatum but not nucleus accumbens. Both treatment groups also showed a significant increase in amphetamine-induced sniffing and repetitive head movements compared to vehicle-treated animals. In contrast, repeated clozapine had no effect on extracellular ascorbate in either neostriatum or nucleus accumbens, but increased the locomotor response to an amphetamine challenge. Thus, to the extent that increases in neostriatal ascorbate exert neuroleptic-like effects, such effects are likely to parallel haloperidol rather than clozapine. 相似文献
13.
Muscarinic cholinergic and alpha 2-adrenergic receptors in the epithelium and muscularis of the human ileum 总被引:2,自引:0,他引:2
The aim of this study was to characterize the binding and functional properties of muscarinic cholinergic (MCh) and alpha 2-adrenergic receptors in the human ileum to provide insight into pharmacologic strategies for managing urinary and fecal incontinence after bladder and rectal replacement with intestinal segments. MCh and alpha 2-adrenergic binding sites were characterized in the epithelium and muscularis of eight human ileal segments with 3H-N-methylscopolamine and 3H-rauwolscine, respectively. The dissociation constant for 3H-N-methylscopolamine in the epithelium and muscularis was 0.32 +/- 0.07 nmol/L and 0.45 +/- 0.10 nmol/L, respectively (p = 0.32). The MCh receptor content was approximately eightfold greater in the muscularis compared with the epithelium (p = 0.008). The dissociation constant for 3H-rauwolscine in the muscularis and epithelium was 2.55 +/- 0.42 nmol/L and 2.03 +/- 0.19 nmol/L, respectively (p = 0.29). The alpha 2-adrenoceptor density was twofold greater in the epithelium compared with the muscularis (p = 0.05). Noncumulative concentration-response experiments were performed with carbachol, an MCh agonist, and UK-14304, a selective alpha 2-adrenergic agonist. The epithelium did not contract in the presence of high concentrations of carbachol and UK-14304. The muscularis preparations were responsive only to carbachol. The muscularis contains primarily MCh receptors mediating smooth muscle contraction. The alpha 2-adrenoceptors are localized primarily to the epithelium and may regulate water secretion in the intestine. The distribution and functional properties of ileal MCh and alpha 2-adrenergic receptors provide a theoretic basis for the treatment of incontinence after bladder and rectal replacement with intestinal segments. 相似文献
14.
Direct measurement of resultant forces in the anterior cruciate ligament. An in vitro study performed with a new experimental technique 总被引:8,自引:0,他引:8
K L Markolf J F Gorek J M Kabo M S Shapiro 《The Journal of bone and joint surgery. American volume》1990,72(4):557-567
A new technique was used to measure the resultant forces in the anterior cruciate ligament during a series of loading experiments on seventeen fresh-frozen cadaver specimens. The base of the ligament's tibial attachment was mechanically isolated with a coring cutter, and a specially designed load-transducer was fixed to the bone-plug that contained the ligament's tibial insertion so that the resultant forces were directly measured by the load-cell. Although the magnitudes of values for forces varied considerably between specimens for a given test condition, the patterns of loading with respect to direction of loading and the angle of flexion of the knee were remarkably consistent. Passive extension of the knee generated forces in the ligament only during the last 10 degrees of extension; at 5 degrees of hyperextension, the forces ranged from fifty to 240 newtons (mean, 118 newtons). When a 200-newton pull of the quadriceps tendon was applied to extend a knee slowly against tibial resistance, however, the force in the ligament increased at all angles of flexion of the knee. Internal tibial torque always generated greater forces in the ligament than did external tibial torque; higher forces were recorded as the knee was extended. The greatest forces (133 to 370 newtons) were generated when ten newton-meters of internal tibial torque was applied to a hyperextended knee. Fifteen newton-meters of applied varus moment generated forces of ninety-four to 177 newtons at full extension; fifteen newton-meters of applied valgus moment generated a mean force of fifty-six newtons, which remained unchanged with flexion of the knee. The force during straight anterior translation of the tibia was approximately equal to the anterior force applied to the tibia. The application of 925 newtons of tibiofemoral contact force reduced the mean force in the ligament that was generated by 200 newtons of anterior pull on the tibia by 36 per cent at full extension and 46 per cent at 20 degrees of flexion. 相似文献
15.
16.
17.
We report a case of recurrent adenocarcinoma in an ileal loop 13 years after cystectomy for adenocarcinoma of the urethra. The method of diagnosis is discussed. 相似文献
18.
A. D. Kirk W. S. Cherikh M. Ring G. Burke D. Kaufman S. J. Knechtle S. Potdar R. Shapiro V. R. Dharnidharka H. M. Kauffman 《American journal of transplantation》2007,7(11):2619-2625
Transplant patients are at the risk for posttransplant lymphoproliferative disease (PTLD), a virally-driven malignancy. Induction with the depleting antibody preparations Thymoglobulin and OKT3 is associated with PTLD suggesting that the T-cell depletion increases PTLD risk. We therefore studied 59 560 kidney recipients from the Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) database for a relationship between induction agent use and PTLD. Two agents with comparable T-cell depletional effects, alemtuzumab and Thymoglobulin, were compared to nondepletional induction agents or no induction. The overall incidence of PTLD was 0.46% and differed significantly by induction strategy (p < 0.01): without induction (0.43%), basiliximab (0.38%), daclizumab (0.33%), Thymoglobulin (0.67%) and alemtuzumab (0.37%). Thymoglobulin was associated with significantly increased PTLD risk (p = 0.0025), but alemtuzumab (p = 0.74), basiliximab (p = 0.33) and daclizumab, which trended toward a protective effect (p = 0.06), were not. Alemtuzumab and Thymoglobulin treated patients did not differ in any established parameter affecting PTLD risk although alemtuzumab is known to have a more pronounced B-cell depleting effect. Interestingly, maintenance therapy with an mTOR inhibitor was strongly associated with PTLD (0.71%, p < 0.0001). Thus, depletional induction is not an independent risk factor for PTLD. Rather, maintenance drug selection or perhaps the balance between B- and T-cell depletion may be more relevant determinants of PTLD risk. 相似文献
19.
Acute Cellular Rejection with CD20-Positive Lymphoid Clusters in Kidney Transplant Patients Following Lymphocyte Depletion 总被引:1,自引:0,他引:1
L. K. Kayler F. G. Lakkis C. Morgan A. Basu D. Blisard H. P. Tan J. McCauley C. Wu R. Shapiro P. S. Randhawa 《American journal of transplantation》2007,7(4):949-954
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup. 相似文献
20.