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   397篇
  免费   32篇
  国内免费   2篇
儿科学   25篇
妇产科学   5篇
基础医学   60篇
口腔科学   3篇
临床医学   21篇
内科学   99篇
皮肤病学   12篇
神经病学   64篇
特种医学   3篇
外科学   32篇
综合类   2篇
预防医学   41篇
眼科学   14篇
药学   11篇
肿瘤学   39篇
  2021年   8篇
  2020年   4篇
  2019年   12篇
  2018年   10篇
  2017年   3篇
  2016年   4篇
  2015年   8篇
  2014年   13篇
  2013年   18篇
  2012年   23篇
  2011年   19篇
  2010年   12篇
  2009年   9篇
  2008年   17篇
  2007年   28篇
  2006年   34篇
  2005年   22篇
  2004年   34篇
  2003年   31篇
  2002年   24篇
  2000年   4篇
  1998年   10篇
  1997年   5篇
  1996年   6篇
  1995年   3篇
  1994年   4篇
  1993年   7篇
  1992年   3篇
  1991年   4篇
  1990年   8篇
  1989年   2篇
  1988年   2篇
  1987年   5篇
  1986年   4篇
  1985年   5篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   3篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   2篇
  1968年   1篇
  1967年   1篇
  1895年   1篇
排序方式: 共有431条查询结果,搜索用时 15 毫秒
51.
Alendronate for osteoporosis in men with androgen-repleted hypogonadism   总被引:1,自引:1,他引:0  
Male hypogonadism is associated with low bone mineral density (BMD) and an increased risk of fractures. Testosterone replacement therapy improves BMD in young hypogonadal men. This effect is milder in older patients, who are at greater risk for fractures. We studied the effects of alendronate or placebo on BMD in 22 osteoporotic men, 29–69 years of age (mean, 50.2±11.2 years) with long-standing hypogonadism, receiving standard testosterone replacement treatment. Alendronate 10 mg daily ( n =11) increased lumbar-spine BMD by 6.0 and 8.4% at 6 and 12 months, respectively, compared with –0.5% at 6 months and +3.3% at 12 months in the placebo group ( n =11; P <0.005). Alendronate also increased mean femoral-neck BMD by 1.9% after 1 year, compared to a 1.4% decrease with placebo ( P <0.005), and increased the total body bone mineral content by 4.4%, compared to a 0.6% decrease with placebo ( P =0.07). After 6 months alendronate suppressed urinary deoxypyridinoline by 50% ( P <0.005), compared to a 24% decrease in the placebo group. Both the alendronate and placebo groups continued with alendronate 70 mg once weekly for the following 2 years. Lumbar-spine BMD during this open-label study phase did not change significantly in the group originally treated with alendronate, but continued to increase in the placebo-alendronate group by 5.4, 6.5, and 6.2% after 18 (6 months of alendronate), 24 and 36 months, respectively ( P <0.05). Femoral-neck BMD continued to increase in both groups receiving active therapy; in the alendronate-alendronate group by 3.7, 2.7, and 5.2% after 18, 24, and 36 months, respectively ( P =0.01), and in the placebo-alendronate group by 0.7 and 1.9% at 24 (first 12 months of alendronate) and 36 months, respectively ( P <0.05). Our results support the long-term administration of alendronate along with testosterone replacement to men with hypogonadism-induced osteoporosis.  相似文献   
52.
Changes in intracellular calcium concentration ([Ca2+]i) in response to topical application of the glutamate agonists N-methyl-d-aspartate (NMDA), or amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were measured in cultured rat hippocampal neurons loaded with Fluo-3 and visualized in a confocal laser scanning microscope. These neurons were subsequently stained for the presence of the enzyme marker for γ-amino butyric acid (GABA), glutamate decarboxylase (GAD). GAD-positive, putative interneurons were less responsive to NMDA and AMPA than GAD-negative neurons. The time course of the rise and decay of [Ca2+]i was similar in the two groups of neurons. Also, there was no clear difference in the shape and size of these two neuron groups indicating that the difference between them is not due to diffusion distances. These data indicate that interneurons are probably more able to handle a calcium load than other neurons, a difference that may underly their resistance to treatments which cause degeneration of other neurons in the hippocampus.  相似文献   
53.
Photodynamic therapy (PDT) is based on the phototoxicity of photosensitizers, mostly porphyrins. Since systemic photodynamic therapy with δ-aminolevulinic acid (δ-ALA) causes prolonged whole-skin photosensitivity, topical photodynamic therapy was developed. We describe the histological findings and the results of immunohistochemical staining for bcl-2 protein in the basal cell carcinoma of a 71-year-old patient treated by photodynamic therapy with δ-ALA. After histological confirmation of the diagnosis, 20%δ-ALA in an aqueous cream base was applied to one lesion for 3 h. After 3 h the tumor was exposed to light emitted by a Kodak carousel light projector. Biopsies were taken before exposure and at days 3 and 21 after exposure. The specimens were stained with hematoxylin-eosin and with monoclonal antibody to bcl-2 protein. The intermediate histological response 3 days after exposure was characterized by "squamoid" transformation of the tumor cells along with signs of necrosis, loss of bcl-2 expression and an inflammatory cell reaction. Clinical and histological examinations 3 weeks after treatment showed no sign of residual tumor.  相似文献   
54.
The septo-hippocampal cholinergic system in rats undergoes rapid activation after acute stress. This is expressed by rapid increases both in high affinity choline uptake and newly synthesized acetylcholine release. Administration of ACTH or corticosterone at a high dose led 10 min later to changes comparable to those observed after acute stress. Choline uptake and acetylcholine release were also elevated 2 days after adrenalectomy. The effects of adrenalectomy could be attenuated by corticosterone, but not by ACTH treatment. The results demonstrate that (a) after short term stress the septo-hippocampal cholinergic system is activated secondary to activation of the pituitary-adrenocortical axis and (b) major changes in circulating corticosterone can modulate the activity of the hippocampal cholinergic synapse.  相似文献   
55.
Breast cancer patients are reported to have a higher rate of second primary malignancies. We retrospectively reviewed the coexistence of breast and gastrointestinal (GI) tumors in the same patients and the characteristics of the tumors. The charts of all patients more than 35 years of age who were diagnosed with breast cancer and hospitalized for various reasons between 1985 and 2003 were reviewed and those who also had a diagnosis of GI malignancy were then selected. Age and tumor characteristics were evaluated. Out of all the patients, 2,650 had a diagnosis of breast cancer, while 40 (1.5%) also had GI malignancies. Among a comparable group of 70,784 consecutive female patients without breast cancer, 1,292 patients (1.8%) had a diagnosis of GI malignancy. The location of GI tumors in patients with both tumors was as follows: stomach, 6 (15%); right colon, 8 (20%); left colon, 7 (17.5%); sigma, 9 (22.5%); and rectum, 10 (25%). Seventeen of the patients (51.5%) had Dukes C and D tumors, 14 (42.5%) Dukes B, and 2 (6%) Dukes A or in situ. The stage of the others was not identified. The mean age at diagnosis of breast cancer was 68.5 years (range 48-88 years). In 23 (57.5%), GI cancer was diagnosed after breast cancer, in 7 (17.5%) it was diagnosed within 3 months of diagnosing breast cancer, and in 8 (20%) it was diagnosed prior to the diagnosis of breast cancer. Five patients suffered from an additional primary cancer: three endometrial, one lung, one esophageal, and one patient had two additional tumors in the endometrium and thyroid. We conclude that the rate of GI malignancies in breast cancer patients is slightly lower than in comparable patients without breast cancer. GI malignancies tend to be diagnosed later and are found more often in the distal colon.  相似文献   
56.
Treatment of adult rats with specific inhibitors of polyamine synthesizing enzymes prevented the early increase in ornithine decar☐ylase activity and polyamine content in the superior cervical ganglion after the postganglionic nerve was cut. Moreover, after axotomy, this treatment led to a marked diminution of the chromatolytic response with a marked neuronal cell death. We conclude that after axonal injury an early increase in polyamine biosynthesis, probably within parent sympathetic neurons, is an obligatory step in the progression of the axon reaction.  相似文献   
57.
Summary The Jerusalem mother and baby unit (MBU) is influenced by the psychoanalytical orientation of the staff, and the historical and cultural conditions surrounding the unit. Forty-three patients with 44 babies (one set of twins) were admitted in 13 years, a rate of admission far from the theoretical demand. Schizophrenia, schizoaffective disorder and mood disorders have been the major diagnoses in more than 50% of the patients.Mothers with schizophrenia were significantly more likely to be admitted sooner after the birth than mothers without schizophrenia (p = 0.025). One infant was separated from the mother on discharge and four recommendations for adoption were given.  相似文献   
58.
59.
Robot-assisted laparoscopic radical prostatectomy (RALP) has gained widespread acceptance in the treatment of prostate cancer. While it increasingly is becoming the surgical approach of choice in many centers, limited data exist directly comparing it to radical retropubic prostatectomy (RRP). This review examines the evidence comparing RALP to RRP. The outcomes evaluated are arranged into perioperative, oncologic, and functional outcomes. Of the 21 publications meeting our selection criteria, Level II, III, and IV evidence were found in 9, 1, and 11 articles, respectively. Overall, RALP was associated with lower blood loss, transfusion rates, length of stay, and higher cost when compared to RRP. Definitive conclusions regarding complications and oncologic and functional outcomes are not yet possible, and will require longer-term follow-up and well-designed randomized controlled trials.  相似文献   
60.
Rare sequence variants may be important in understanding the biology of common diseases, but clearly establishing their association with disease is often difficult. Association studies of such variants are becoming increasingly common as large-scale sequence analysis of candidate genes has become feasible. A recent report suggested SLITRK1 (Slit and Trk-like 1) as a candidate gene for Tourette Syndrome (TS). The statistical evidence for this suggestion came from association analyses of a rare 3'-UTR variant, var321, which was observed in two patients but not observed in more than 2000 controls. We genotyped 307 Costa Rican and 515 Ashkenazi individuals (TS probands and their parents) and observed var321 in five independent Ashkenazi parents, two of whom did not transmit this variant to their affected child. Furthermore, we identified var321 in one subject from an Ashkenazi control sample. Our findings do not support the previously reported association and suggest that var321 is overrepresented among Ashkenazi Jews compared with other populations of European origin. The results further suggest that overrepresentation of rare variants in a specific ethnic group may complicate the interpretation of association analyses of such variants, highlighting the particular importance of precisely matching case and control populations for association analyses of rare variants.  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