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   11881篇
  免费   823篇
  国内免费   32篇
耳鼻咽喉   255篇
儿科学   373篇
妇产科学   226篇
基础医学   1757篇
口腔科学   130篇
临床医学   1545篇
内科学   2369篇
皮肤病学   300篇
神经病学   1126篇
特种医学   473篇
外科学   1255篇
综合类   108篇
一般理论   8篇
预防医学   1119篇
眼科学   152篇
药学   754篇
中国医学   16篇
肿瘤学   770篇
  2023年   82篇
  2022年   143篇
  2021年   298篇
  2020年   175篇
  2019年   287篇
  2018年   325篇
  2017年   229篇
  2016年   284篇
  2015年   309篇
  2014年   363篇
  2013年   488篇
  2012年   744篇
  2011年   710篇
  2010年   397篇
  2009年   390篇
  2008年   585篇
  2007年   655篇
  2006年   578篇
  2005年   628篇
  2004年   581篇
  2003年   574篇
  2002年   510篇
  2001年   236篇
  2000年   221篇
  1999年   228篇
  1998年   136篇
  1997年   113篇
  1996年   88篇
  1995年   108篇
  1994年   56篇
  1993年   84篇
  1992年   136篇
  1991年   122篇
  1990年   144篇
  1989年   126篇
  1988年   94篇
  1987年   95篇
  1986年   88篇
  1985年   93篇
  1984年   101篇
  1983年   65篇
  1982年   70篇
  1981年   45篇
  1980年   54篇
  1979年   76篇
  1976年   53篇
  1974年   57篇
  1973年   60篇
  1972年   47篇
  1971年   45篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
This paper reviews systematic toxicological analysis (STA) procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology or doping control using gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, thin-layer chromatography and capillary electrophoresis. Papers from 1992 to 1998 have been taken into consideration. Screening procedures in biosamples (whole blood, plasma, serum, urine, vitreous humor, brain, liver or hair) of humans or animals (horse, or rat) are included for the following drug classes: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (AT-II) blockers, anticoagulants of the 4-hydroxy coumarin type, barbiturates, dihydropyridine calcium channel blockers (calcium antagonists), diuretics, hypoglycemic sulfonylureas and non-steroidal anti-inflammatory drugs (NSAIDs). Methods for confirmation of preliminary results obtained by screening procedures using immunoassay or chromatographic techniques are also included. Furthermore, procedures for the simultaneous detection of several drug classes are reviewed. The toxicological question to be answered and the consequences for the choice of an adequate method, the sample preparation and the chromatography itself are discussed. The basic information about the biosample assayed, work-up, separation column, mobile phase or separation buffer, detection mode and validation data of each procedure is summarized in 16 tables. They are arranged according to the drug class and the analytical method. Examples of typical applications are presented. Finally, STA procedures are reviewed and described allowing simultaneous screening for different (acidic) drug classes.  相似文献   
73.
74.
Gabapentin, a novel antiepileptic drug, is effective in the treatment of partial seizures with and without secondary generalization. Evidence suggests that it may have mood-stabilizing and possibly antidepressant properties in bipolar depression. We report on a 48-year-old woman who had recurrent major depressive disorder. Following inguinal herniorrhaphy, she developed severe stabbing pain in the lower abdomen and inguinal area that progressed to constant pain in her whole body. She was depressive, hopeless, and had given up her social activities. A diagnosis of major depressive disorder and somatoform pain disorder was made. Antidepressants and carbamazepine were ineffective, and she had attempted suicide. Gabapentin resulted in remission of both the pain and the depressive mood at a dose of 1.800 mg/day.  相似文献   
75.
Multicellular contact has been shown to influence the in vitro sensitivity of cells to drug treatment. We investigated the use of macroporous gelatin microcarriers, CultiSpher-G, as a convenient laboratory system for the molecular analysis of this "contact effect". We determined that human A549 cells can be grown in CultiSphers with growth and cell cycle parameters similar to those of monolayers. In addition, cells in CultiSphers express less p27/kip1, an indicator of cell cycle arrest, than equivalent cells in monolayers. When treated with drugs, A549 cells grown in CultiSphers or monolayers accumulate equivalent amounts of platinum-DNA adducts and similar amounts of doxorubicin. Moreover, A549 and KB-3-1 cells in CultiSphers have significantly decreased sensitivity to cis-platinum(II)diammine dichloride (cisplatin), 4-hydroperoxycyclophosphamide, doxorubicin, and paclitaxel (taxol) compared with cells in monolayers when assayed by clonogenic survival. Cisplatin treatment in monolayers or CultiSphers did not result in apoptotic cell death. In contrast, paclitaxel caused a significant amount of sub-G1 DNA, an indicator of apoptosis, which was diminished when cells were grown in CultiSphers compared with monolayers. When grown in CultiSphers, cells with abrogated p53 function (A549/16E6 and NCI-H1299) were less sensitive to cisplatin than the corresponding monolayer cells, indicating that the decrease in sensitivity is p53 independent. Taken together, the data suggest that CultiSpher-G microcarriers are a useful in vitro system to examine the effects of three-dimensional cell contact on drug sensitivity of human tumor cells.  相似文献   
76.
Rationale: The intensity dependence of the auditory evoked potentials (AEP) has been suggested to be a specific biological marker of central serotonergic activity. Objective: While previous studies used circumstantial evidence to support this hypothesis, we manipulated (decreased) cerebral levels of serotonin directly by using tryptophan depletion. Methods: Twelve healthy young subjects were investigated using placebo and two different amino acid mixtures in a double blind cross over design on three different occasions. AEPs recorded during tryptophan depletion were analyzed by dipole analysis and regional sources using methods published in the literature. Results: For none of the mixtures a significant effect of tryptophan depletion was found. There was a trend towards reduced intensity dependency after tryptophan depletion, especially in the right hemisphere. This reduction correlated with the amount of reduced tryptophan in plasma. Conclusions: The results indicate, in contrast to earlier indirect studies, that the intensity dependence of AEPs is not a specific marker of central serotonergic activity. Received: 8 March 1999 / Final version: 25 May 1999  相似文献   
77.
The chromosomes of metastatic cells and polyploid levels in the bone marrow of 26 patients with small cell anaplastic carcinoma were studied by direct bone marrow preparation and trypsin-Giemsa banding. Eighteen of these patients had received no tumor therapy and 8 had had chemotherapy and/or radiation therapy; 18 patients, including 5 who had received therapy, had karyotypic abnormalities with or without elevation of the polyploid level. Modal numbers and chromosome abnormalities were highly variable in treated and untreated patients. Modes ranged from hypodiploid to polyploid, but polyploid modes were the most frequently observed abnormal modes. Polyploid modes were not seen, however, in post-therapy patients with the exception of one who had received radiation therapy to the mediastinum for only 4 days prior to withdrawal of the specimen for chromosome analysis. Ten patients had elevated polyploid levels that ranged from 4.24 to 44.8% and always occurred in conjunction with karyotypic abnormalities. Both aneusomy (abnormal number) of normal chromosomes and structural aberrations (markers) occurred frequently. Some markers were consistent within an individual, but other variable aberrations were also typically present. Very few markers were common to 2 or more patients. The no. 1 chromosome participated in marker formation in 14 of the 18 patients with karyotypic abnormalities. Of the 26 patients, 5 were negative for metastasis to the marrow by pathologic examination but positive by cytogenetic diagnosis, whereas none were positive by pathologic examination and negative by cytogenetic diagnosis; this demonstrated that cytogenetics may be used as a rapid adjunct diagnostic procedure for the detection of metastasis in the marrow.  相似文献   
78.
Intraoperative color Doppler recordings, obtained either from the epicardial or transesophageal approach, offer real-time information about the presence and severity of mitral regurgitation at the time of surgery. The technique allows instantaneous evaluation of mitral and tricuspid repair and may offer important information about the postoperative outcome.  相似文献   
79.
Twenty-nine children (24, male; 5, female) with non-disseminated rhabdomyosarcomas of the bladder or prostate were treated (1978-1980) by a primary chemotherapy regimen consisting of vincristine, actinomycin D, and cyclophosphamide ("Pulse" VAC), with or without local radiotherapy. During the initial 20 wk of chemotherapy, nine children achieved a Clinical Complete Response (CCR). Three of these are without evidence of disease (NED) and have functional bladders, two following partial cystectomy. Four who achieved a CCR subsequently relapsed or remained biopsy positive, but are at present NED following radiotherapy and anterior exenteration. Two patients who achieved CCR status relapsed and have died of disease. Twelve patients had a Clinical Partial Response (CPR) in less than 20 wk and two others in less than 40 wk. Seven of these are NED with intact bladders following chemotherapy-radiotherapy; and an additional patient is NED following partial cystectomy. Four patients in the CPR group have been treated by exenteration following failure to achieve complete response, and are NED. One patient has died, and one has progressive disease. Six patients had an inadequate response to chemotherapy (NR). Anterior exenteration was carried out in three, and two of these have survived. The overall results in these 29 patients are: (A) alive and disease-free with functional bladders, 11; (B) alive and disease-free following anterior exenteration, 10; and (C) dead or death from tumor anticipated, 8. The function of retained bladders (11) has been satisfactory.  相似文献   
80.
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