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   31476篇
  免费   2028篇
  国内免费   140篇
耳鼻咽喉   364篇
儿科学   864篇
妇产科学   588篇
基础医学   3519篇
口腔科学   698篇
临床医学   2590篇
内科学   6835篇
皮肤病学   521篇
神经病学   1762篇
特种医学   945篇
外国民族医学   5篇
外科学   5260篇
综合类   1001篇
一般理论   25篇
预防医学   2312篇
眼科学   871篇
药学   3064篇
  1篇
中国医学   347篇
肿瘤学   2072篇
  2023年   317篇
  2022年   914篇
  2021年   1285篇
  2020年   798篇
  2019年   1050篇
  2018年   1225篇
  2017年   809篇
  2016年   819篇
  2015年   967篇
  2014年   1277篇
  2013年   1576篇
  2012年   2305篇
  2011年   2295篇
  2010年   1400篇
  2009年   1011篇
  2008年   1670篇
  2007年   1667篇
  2006年   1513篇
  2005年   1397篇
  2004年   1226篇
  2003年   1059篇
  2002年   936篇
  2001年   734篇
  2000年   652篇
  1999年   547篇
  1998年   215篇
  1997年   156篇
  1996年   153篇
  1995年   161篇
  1994年   108篇
  1993年   124篇
  1992年   271篇
  1991年   269篇
  1990年   239篇
  1989年   241篇
  1988年   184篇
  1987年   216篇
  1986年   167篇
  1985年   175篇
  1984年   151篇
  1983年   109篇
  1982年   79篇
  1981年   89篇
  1980年   67篇
  1979年   138篇
  1978年   88篇
  1977年   88篇
  1975年   84篇
  1974年   70篇
  1973年   75篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Using immunohistochemical and biochemical techniques, the occurrence of endogenous opioid peptides and their receptors in normal rat bone and joint tissues was investigated. Opioid receptors were detected, quantified, and characterized in homogenates from capsule/synovium and periosteum using radioligand binding assays. Receptor binding of the nonselective opioid [3H]naloxone to tissue homogenates was stereospecific and saturable, showing similar characteristics to that of brain tissue, although with lower binding capacities. By immunohistochemistry, the neuronal occurrence of four different enkephalins was demonstrated in synovium, bone marrow, periosteum, and juxta-articular bone, whereas no neuronal dynorphin immunoreactivity was detected. Double-staining studies disclosed that enkephalins coexisted with substance P in primary afferent fibers. The applied techniques can be used to assess changes in the distribution of endogenous opioids and their receptors in joint tissues in conditions associated with pain and inflammation. The endogenous opioid system now demonstrated might be targeted and exploited therapeutically to obtain peripheral control of symptoms in joint disorders.  相似文献   
82.
Gall bladder hydatid cyst is a rare entity. Concurrent occurrence of gall blader hydatid cysts along with liver cysts, especially with the biliary channels clear of cysts, is very rare. We report a 27-year-old man with a gall bladder hydatid cyst that was diagnosed only after opening the resected specimen of the gall bladder.  相似文献   
83.
Either a percutaneous-transvesical, a transvaginal, or a perurethral-transvesical approach can be used for oocyte recovery under ultrasound guidance in an in vitro fertilization and embryo transfer program. After having experienced these three different approaches in our program, we preferentially used the perurethral-transvesical approach as our routine technique for oocyte recovery under ultrasound guidance. We feel that this method is easier to perform and also carrier less risk for contamination. From January to December 1986, 186 oocyte retrievals under ultrasound guidance were performed. In 7 cases no oocytes were found despite normal ovarian stimulation. A total of 767 oocytes was collected; the fertilization rate was 71.8%. Forty pregnancies were achieved (21.5% per attempt or 27.7% per embryo replacement). Except for transient hematuria, no complications were observed.  相似文献   
84.
Z Khan  V K Singh  W C Yang 《Urology》1992,40(3):289-291
This is the first report of incidence of neurogenic bladder in patients with acquired immune deficiency syndrome (AIDS) and emphasizes that it is a significant cause of various voiding dysfunctions in these patients. Neurologic disease occurs in about one third of patients with AIDS. Both central and peripheral nervous systems may be involved. Urodynamic evaluation is necessary for assessment and management of neurogenic voiding disorders in this group of patients.  相似文献   
85.
Abstract: In order to determine the pulmonary toxicity of kerosene and its ignition product (soot) in asbestos exposed subjects, the activities of phase I and phase II drug metabolizing enzymes in rat lungs after single intratracheal coexposure to Indian chrysotile asbestos and kerosene or its soot and Indian chrysotile were assayed. Exposure to kerosene or its soot resulted in a significant increase in the level of microsomal cytochrome P-450 and the activity of P-450 dependent monooxygenase, benzo(a)pyrene hydroxylase, as well as in the activities of microsomal epoxide hydrase and cytosolic glutathione-S-transferase (GST). However, in chrysotile exposed animals a reverse pattern in these parameters was recorded. The co-exposure to chrysotile and kerosene or chrysotile and soot led to a significant depletion in cytochrome P-450 level and a decrease in the activities of benzo(a)pyrene hydroxylase, epoxide hydrase and GST when compared to kerosene and soot controls, respectively. These results suggest that asbestos by altering the pulmonary drug metabolizing enzyme system may increase the toxic potential of kerosene and its ignition product in the respiratory system.  相似文献   
86.
We describe 100 consecutive patients with histologically proven gastric carcinoma who were admitted to various hospitals in Northern Pakistan. Twenty-six per cent of patients were under 40 years of age. In a majority of patients the tumour was of a morphological type associated with poor prognosis. In most cases the disease was already at an advanced stage at the time of diagnosis, and most patients died within one year.  相似文献   
87.
Both conception and successful completion of pregnancy are rare occurrences in female patients on chronic renal replacement therapy. Only a handful of successful pregnancies and deliveries have been reported in patients receiving hemodialysis (HD). Even less common are reports of successful pregnancy and delivery in patients receiving chronic ambulatory peritoneal dialysis (CAPD). Among the more common causes of fetal loss are abruptio placentae and other causes of spontaneous miscarriage. We report here three cases of pregnancy in patients on CAPD; two of these pregnancies progressed successfully to spontaneous delivery, while the third terminated during an episode of acute peritonitis. Furthermore, we have reviewed the literature concerning the outcome of pregnancy in the dialysis population on CAPD.  相似文献   
88.
89.
We have studied the effect of dietary fish oil supplementation (3.2 gm/day of eicosapentaenoic acid and 2.2 gm/day of docosahexaenoic acid) for 10 weeks on the antigen-induced, cutaneous late-phase response (LPR) in 16 atopic individuals. All subjects developed an LPR to intradermal allergen injection. The mean +/- SEM area of induration at 6 hours was 1840 +/- 472 mm2. A biopsy was performed at the LPR site at 6 hours. Subjects were then randomized to receive fish oil or placebo olive oil in a double-blind, parallel fashion, for 10 weeks. After the diet, there were no significant differences between fish oil and placebo treatment in the size of the immediate wheal-and-flare response or the extent of induration at 4 and 6 hours, as compared with prediet values in each group. Histologically, at 6 hours, there was a significant infiltrate into the allergen site compared with that of the control diluent site of total inflammatory cells (p less than 0.002) as well as of eosinophils (p less than 0.001). However, there were no significant differences when pre- and postdiet values were compared. Hence, we conclude that dietary fish oil supplementation does not inhibit the cutaneous LPR clinically or histologically.  相似文献   
90.
A multicenter, randomized placebo-controlled double-blind trial of nimodipine in poor-grade aneurysm patients was carried out in 17 Canadian hospitals. Of 188 patients enrolled in the trial, 32 were excluded for protocol violations and two were excluded due to statistical considerations, leaving 154 patients for valid outcome analysis. Nimodipine treatment was associated with a significantly better outcome (p less than 0.001): 21 (29.2%) of 72 nimodipine-treated patients had a good outcome at 3 months after subarachnoid hemorrhage (SAH) compared to eight (9.8%) of 82 placebo-treated patients. Delayed ischemic deficits from vasospasm alone were significantly less frequent in the nimodipine group (p less than 0.05) with permanent deficits occurring in five nimodipine-treated patients (6.9%) and in 22 placebo-treated patients (26.8%). Improvement in the good outcome rate and reduction in delayed ischemic deficits from vasospasm alone occurred in both Grade 3 and 4 patients, with no difference between nimodipine- and placebo-treated patients being found in Grade 5 patients. Repeat angiography after Day 4 was carried out in 124 patients. There was no significant difference in the incidence of moderate or severe diffuse spasm, which was seen in 64.3% of nimodipine-treated patients and 66.2% of placebo-treated patients. The authors conclude that nimodipine treatment in poor-grade patients with SAH results in an increase in the number of good outcomes and a reduction in the incidence of delayed neurological deterioration due to vasospasm. This effect occurs by a mechanism other than prevention of large-vessel spasm as visualized on angiography.  相似文献   
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