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   3433597篇
  免费   282045篇
  国内免费   13325篇
耳鼻咽喉   46803篇
儿科学   109002篇
妇产科学   89239篇
基础医学   547095篇
口腔科学   92815篇
临床医学   312943篇
内科学   605881篇
皮肤病学   91131篇
神经病学   293479篇
特种医学   133862篇
外国民族医学   288篇
外科学   523829篇
综合类   102240篇
现状与发展   24篇
一般理论   2359篇
预防医学   294218篇
眼科学   77972篇
药学   234723篇
  27篇
中国医学   9326篇
肿瘤学   161711篇
  2021年   54857篇
  2020年   34962篇
  2019年   57870篇
  2018年   71116篇
  2017年   54227篇
  2016年   59627篇
  2015年   73795篇
  2014年   107862篇
  2013年   172957篇
  2012年   93543篇
  2011年   94015篇
  2010年   116703篇
  2009年   121062篇
  2008年   81237篇
  2007年   84661篇
  2006年   94585篇
  2005年   90313篇
  2004年   91915篇
  2003年   82657篇
  2002年   72503篇
  2001年   102455篇
  2000年   95120篇
  1999年   95185篇
  1998年   64514篇
  1997年   62574篇
  1996年   60731篇
  1995年   56166篇
  1994年   50425篇
  1993年   47102篇
  1992年   67525篇
  1991年   64782篇
  1990年   61416篇
  1989年   60587篇
  1988年   56419篇
  1987年   55184篇
  1986年   52616篇
  1985年   52207篇
  1984年   48135篇
  1983年   44307篇
  1982年   41696篇
  1981年   39417篇
  1980年   37150篇
  1979年   40649篇
  1978年   36250篇
  1977年   32830篇
  1976年   30116篇
  1975年   28998篇
  1974年   30482篇
  1973年   29595篇
  1972年   27850篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Summary A new modification of microvenous anastomosis, which has increased patency rates while simultaneously decreasing the difficulty of the procedure, is presented in this paper. The primary purpose of this study was to compare the classical and the temporary stent techniques of microvenous anastomosis. Because of problems such as mixing and tangling of strings during insertion and tying of the last four sutures while applying the temporary stent technique, we decided to modify the procedure. The silastic tube was removed through an incision (venotomy), distant from the actual suture line. This modified technique and the other above mentioned techniques were carried out on rat femoral veins. The results indicate that this modification has increased patency rates, shortened the time of anastomosis and facilitated the procedure.  相似文献   
992.
W C Hsiao  P Braun  E R Becker  S R Thomas 《JAMA》1987,258(6):799-802
This article describes the design and methods of a study currently under way to develop a Resource-Based Relative Value Scale (RBRVS); an alternative basis for establishing the payment rate for the services and procedures (S/Ps) of physicians in medical and surgical specialties. Physician resource inputs to be measured include (1) S/P time, (2) pre-S/P and post-S/P times, (3) intensity, (4) practice costs, including malpractice premiums, and (5) the cost of specialty training. These five factors will be combined to produce an RBRVS denominated in nonmonetary units. In the initial phase of the study, data on time and intensity will be obtained through a national survey of physicians who perform these S/Ps. In the second, consensus phase of the project, the investigators will convene a panel of representatives of the medical profession, third-party payers, consumers, and other interested parties to examine areas of agreement and disagreement as to how an RBRVS should be used for policy purposes. The final results of this study are expected by the summer of 1988.  相似文献   
993.
994.
Using cortical cups in chloralose-urethanized rats, the in vivo release of cholecystokinin-like immunoreactivity (CCK-LI) from cerebral cortex was examined. Resting levels of cholecystokinin-like immunoreactivity ranged from 20 to 30 pg/20 min sample. The addition of potassium (40 mM) in excess, resulted in a highly significant elevation in the levels of CCK-LI in the cortical superfusate. Deletion of calcium and the substitution of cobalt (10 mM), resulted in a significant reduction in both resting release and the release otherwise evoked by the addition of potassium. Focal electrical stimulation of the cortex (20 Hz), resulted in a significant (1.9 +/- 0.2-fold, n = 8) increase in the levels of CCK-LI. The addition of glutamate (10(-6)-10(-4) M) of kainic acid (10(-8)-10(-6) M), also resulted in significant elevations in the levels of CCK-LI. The co-administration of a putative glutamate receptor antagonist, kynurenic acid (10(-4) M) resulted in a significant reduction in the levels of release otherwise evoked by the addition of glutamate, but not by electrical stimulation. The addition of GABA (10(-5)-10(-3) M) resulted in a dose-dependent decrease in the resting release of CCK-LI, and the release evoked by glutamate. Picrotoxin (10(-6)-10(-4) M), resulted in a highly significant increase in the levels of CCK-LI in the cortical effluent. These results are consistent with a tonic GABAergic inhibition of CCK-releasing neurons. The treatment of the animal with diazepam (30 mg/kg, i.p.) also resulted in a significant reduction in resting release and the release otherwise evoked by focal cortical stimulation.  相似文献   
995.
Pharmacokinetics of the cis-platin analog ethylenediaminemalonatoplatinum(II) (JM-410) was studied in 28 cycles of 19 patients during the phase I study of this drug. The drug was administered intravenously by short-term (10-60 min) infusion. Doses ranged from 20 to 1,200mg m-2. JM-40 was determined in plasma ultrafiltrate and urine by HPLC. Platinum (Pt) concentrations were determined in plasma, plasma ultrafiltrate, urine and red blood cells by atomic absorption spectrometry up to 5 days after administration of the drug. Ultrafilterable Pt could be determined up to 45 days after the infusion in one patient sampled over such a long period. Pharmacokinetics of JM-40 showed a linear behaviour. The final half-life of total Pt in plasma was 4.1 +/- 0.9 days. The disposition of JM-40 was similar to that of ultrafilterable Pt in respect to t1/2 alpha (10 and 13 min), t1/2 beta (44 and 57 min), volumes of distribution Vc (11 and 121) and Vss (17 and 201), systemic clearance (256 and 223 ml min-1), renal clearance (69 and 73 ml min-1) and metabolic clearance (183 and 154 ml min-1). During the first 6 h 27 +/- 9% of the administered dose was excreted as JM-40. Cumulative platinum excretion in the urine amounted to 29 +/- 13% and 60 +/- 13% over the first 6 h, 24 h and 5 days, respectively. The uptake of platinum in red blood cells was limited, comprising only 0.24 +/- 0.12% of the administered dose. Although JM-40 and carboplatin are structurally closely related, pharmocokinetics and toxicity of JM-40 were more similar to cis-platin than to carboplatin.  相似文献   
996.
Perceptual asymmetry on a series of four specially constructed dichotic word tests was found to change as a function of the emotional quality of the words in the tests (P = 0.05). This was most pronounced in the case of positively valued words which produced an increase in asymmetry consistent with facilitated left-hemisphere function (P less than 0.004). Changes in asymmetry with emotion differed as a function of personality characteristics of the subjects, with repressors and high anxious subjects showing an increase with emotion while true low anxious subjects showed a decrease (P less than 0.02). Personality groups also differed in asymmetry on an emotionally neutral test (P less than 0.04) and in changes in asymmetry over time independent of emotion (P less than 0.001). These data suggest that emotion mediated activation of the left hemisphere may facilitate information processing within that hemisphere. Moreover, they indicate that dichotic listening tests may provide a non-invasive and inexpensive method for assessing emotion mediated changes in brain state that are clinically relevant.  相似文献   
997.
The complete medical records of 122 patients who sustained traumatic spinal cord injuries were reviewed to determine the frequency and results of emergency room assessments for loss of consciousness (LOC) and post-traumatic amnesia (PTA). Eighty-eight percent of the patients were assessed for LOC and 19% were assessed for PTA. Fifty patients (41% of the total population) admitted to LOC, PTA or both. Fourteen of these 50 patients underwent subsequent radiographic examinations of the skull, all of which were negative. Because of the association of intracranial complications and long-term cognitive sequelae with even brief LOC or PTA, early recognition of craniocerebral trauma is an important component of the acute management of spinal cord injured patients.  相似文献   
998.
Polymorphonuclear leukocyte (PMN) migration was assessed in vitro using the agarose plate method in patients with psoriasis vulgaris, and compared with an age- and sex-matched control group. No significant difference was found between the two groups in the PMN response to the chemotactic substances F-Met-Leu-Phe (FMLP) or zymosan activated serum (ZAS). Equally, the chemokinetic or chemotactic potential of psoriatic serum did not differ from control serum. Our results do not support a primary abnormality of PMN function in psoriasis.  相似文献   
999.
Chlothorax is a rare complication of high translumbar aortography and a case is described here.  相似文献   
1000.
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