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   5106篇
  免费   476篇
  国内免费   87篇
耳鼻咽喉   50篇
儿科学   123篇
妇产科学   146篇
基础医学   667篇
口腔科学   55篇
临床医学   469篇
内科学   1254篇
皮肤病学   72篇
神经病学   390篇
特种医学   150篇
外科学   742篇
综合类   120篇
一般理论   3篇
预防医学   274篇
眼科学   158篇
药学   386篇
中国医学   24篇
肿瘤学   586篇
  2023年   44篇
  2022年   94篇
  2021年   164篇
  2020年   122篇
  2019年   187篇
  2018年   168篇
  2017年   131篇
  2016年   146篇
  2015年   191篇
  2014年   215篇
  2013年   249篇
  2012年   351篇
  2011年   355篇
  2010年   212篇
  2009年   182篇
  2008年   273篇
  2007年   294篇
  2006年   260篇
  2005年   239篇
  2004年   206篇
  2003年   202篇
  2002年   175篇
  2001年   118篇
  2000年   122篇
  1999年   82篇
  1998年   52篇
  1997年   36篇
  1996年   36篇
  1995年   26篇
  1994年   27篇
  1993年   33篇
  1992年   66篇
  1991年   59篇
  1990年   78篇
  1989年   53篇
  1988年   55篇
  1987年   53篇
  1986年   38篇
  1985年   48篇
  1984年   35篇
  1983年   25篇
  1982年   16篇
  1981年   17篇
  1980年   16篇
  1979年   17篇
  1978年   17篇
  1977年   11篇
  1976年   14篇
  1974年   10篇
  1973年   9篇
排序方式: 共有5669条查询结果,搜索用时 31 毫秒
61.
Recent studies demonstrate that cellular, molecular and morphological changes induced by stress in rats are accelerated when there is a pre-existing strain upon their already compromised adaptive responses to internal or external stimuli, such as may occur with uncontrolled diabetes mellitus. The deleterious actions of diabetes and stress may increase oxidative stress in the brain, leading to increases in neuronal vulnerability. In an attempt to determine if stress, diabetes or stress+diabetes increases oxidative stress in the hippocampus, radioimmunocytochemistry was performed using polyclonal antisera that recognize proteins conjugated by the lipid peroxidation product 4-hydroxy-2-nonenal (HNE). Radioimmunocytochemistry revealed that HNE protein conjugation is increased in all subregions of the hippocampus of streptozotocin (STZ) diabetic rats, rats subjected to restraint stress and STZ diabetic rats subjected to stress. Such increases were not significant in the cortex. Because increases in oxidative stress may contribute to stress- and diabetes-mediated decreases in hippocampal neuronal glucose utilization, we examined the stress/diabetes mediated HNE protein conjugation of the neuron specific glucose transporter, GLUT3. GLUT3 immunoprecipitated from hippocampal membranes of diabetic rats subjected to stress exhibited significant increases in HNE immunolabeling compared to control rats, suggesting that HNE protein conjugation of GLUT3 contributes to decreases in neuronal glucose utilization observed during diabetes and exposure to stress. Collectively, these results demonstrate that the hippocampus is vulnerable to increases in oxidative stress produced by diabetes and stress. In addition, increases in HNE protein conjugation of GLUT3 provide a potential mechanism for stress- and diabetes-mediated decreases in hippocampal neuronal glucose utilization.  相似文献   
62.
To express the core protein of HIV-1 of Chinese prevalent strain (HIV-1 (CN)) in Pichia pastoris, the fulllength gag gene was inserted into the secretory expression vector pHILS1. Linearized recombinant plasmid pHILGAG by Sail was electrotransformed into the yeast strain GS115, and the yeast transformants were identified by PCR. To induce the interest protein to be expressed, the PCR positive transformants were inoculated in the medium of BMGY and BMMY, mRNA of the strain was detected by RT-PCR, and the expressed protein was analyzed by SDS-PAGE, Western blotting and thin layer scanning. mRNA (1.3 kb) was amplified by RT-PCR. SDS-PAGE and Western blotting analysis showed that the molecular mass of the expressed protein was 55 kD, which was similar to the expected value, and the expressed protein could react with McAb to HIV-1 p24. Thin layer scanning analysis demonstrated that the whole amount of the expressed protein was approximately 13 % of the soluble protein in the supernatant. The recombinant yeast had good genetic stability. The optimal expression conditions of the engineering yeast were as follows: BMMY medium, 80-90% of dissolved oxygen, 1% methanol, and 3-day-cultivation course. Gag proteins were expressed under the optimal expression condition and purified via gel filtration chromatography. The purity of the interest protein was up to 85 %. After the purified proteins were inoculated into BALB/c mice, the anti-HIV-1 antibodies in the immunized mice could be detected by Western blotting.  相似文献   
63.
BACKGROUND: This randomized controlled trial assessed the safety and effects of twice-weekly weight training among recent breast cancer survivors. Outcomes included body size and biomarkers hypothesized to link exercise and breast cancer risk. METHODS: A convenience sample of 85 recent survivors was randomized into immediate and delayed treatment groups. The immediate group trained from months 0 to 12; the delayed treatment group served as a no exercise parallel comparison group from months 0 to 6 and trained from months 7 to 12. Measures at baseline, 6 and 12 months included body weight, height, body fat, lean mass, body fat %, and waist circumference, as well as fasting glucose, insulin, insulin resistance, insulin-like growth factor-I (IGF-I), IGF-II, and IGF-binding protein-1, IGFBP-2, and IGFBP-3. Injury reporting was standardized. RESULTS: The intervention resulted in significant increases in lean mass (0.88 versus 0.02 kg, P < 0.01), as well as significant decreases in body fat % (-1.15% versus 0.23%, P = 0.03) and IGF-II (-6.23 versus 28.28 ng/mL, P = 0.02) comparing immediate with delayed treatment from baseline to 6 months. Within-person changes experienced by delayed treatment group participants during training versus no training were similar. Only one participant experienced a study related injury that prevented continued participation. CONCLUSION: Twice-weekly weight training is a safe exercise program for recent breast cancer survivors that may result in increased muscle mass, as well as decreased body fat % and IGF-II. The implications of these results on cancer recurrence or survival may become more evident with longer exercise intervention trials among breast cancer survivors.  相似文献   
64.
PURPOSE: We performed a phase I study of a day (D) 1 and D4 bortezomib administration once every 2 weeks to determine the recommended phase II dose and toxicity profile, and the extent of 20S proteasome inhibition obtained. PATIENTS AND METHODS: Patients with solid tumors or lymphomas were treated with bortezomib at 0.25 to 1.9 mg/m2 on D1 and D4, every 2 weeks. 20S proteasome levels in blood were assayed at baseline and at 1, 4, and 24 hours postdose in cycle 1. RESULTS: On this D1 and D4 every 2 weeks' schedule, dose-limiting toxicity (DLT) was evident at the 1.75 and 1.9 mg/m2 dose levels, most commonly in patients receiving individual total doses > or = 3.0 mg. The main DLT was peripheral neuropathy evident at the higher doses and in patients previously exposed to neurotoxic agents. Other DLTs included diarrhea and fatigue; grade 3 thrombocytopenia was also noted. Reversible inhibition of 20S proteasome activity was dose dependent and best fit a total dose (mg) per fraction rather than mg/m2; 70% of baseline activity was inhibited by a dose of 3.0 to 3.5 mg given on D1 and on D4 every other week. Antitumor effects short of confirmed partial responses were observed in patients with melanoma, non-small-cell lung cancer, and renal cell carcinoma. CONCLUSION: Bortezomib (PS-341) is a novel antineoplastic agent that is well tolerated at doses not exceeding 3.0 mg (equivalent to 1.75 mg/m2), repeated on D1 and D4 every other week. This dose correlates with 70% inhibition of 20S proteasome activity. DLTs include neuropathy, fatigue, and diarrhea.  相似文献   
65.
66.
67.
68.

Ethnopharmacological relevance

Lignosus rhinocerus (known locally as ‘Tiger Milk mushroom’) is the most important medicinal mushroom used by the indigenous communities of Malaysia to treat fever, cough, asthma, cancer, food poisoning and as a general tonic. The sclerotium of the mushroom is the part with medicinal value. Lignosus rhinocerus was hitherto unexploited commercially because of limited supply. Recently, the mushroom was successfully cultivated.

Materials and methods

Sprague Dawley rats (5 rats/group/sex) were fed orally with 250, 500 and 1000 mg/kg TM02, 1000 mg/kg TM03 as well as 1000 mg/kg wild type Lignosus rhinocerus sclerotial powder. Sclerotial powder was orally administered once daily and consecutively for 28 days. Body weight of each animal was measured and any gross behavioral change was observed daily. Hematological and clinical biochemical parameters as well as histopathological analysis were carried out on 29th day.

Results

The results showed that oral administration of the sclerotial powder at daily dose of up to 1000 mg/kg had no adverse effect on the growth rate, hematological and clinical biochemical parameters (including renal and liver function parameters). Histological studies showed that the treatments did not induce any pathological changes in the liver, kidney, heart, spleen and lung of the animals.

Conclusion

In conclusion, our results show that there was no treatment-related sub-acute toxicity in rats following 28-days oral administration of 250, 500 and 1000 mg/kg TM02, 1000 mg/kg TM03 as well as 1000 mg/kg wild type Lignosus rhinocerus sclerotial powder. As the highest tested dose of 1000 mg/kg was not associated with any toxicity concern, the NOAEL dose is higher than 1000 mg/kg.  相似文献   
69.
Two patients (two men, 56 and 59 years old) had sphenoid sinus mucocele originating in the anterior clinoid process. In one case the mucocele initially mimicked diabetic ophthalmoplegia with pupil-sparing palsy of the oculomotor (third) nerve. After resolution of the palsy, severe visual loss developed with minimal recovery of vision after surgery. The second patient had recurrent episodes of retrobulbar optic neuropathy with optic atrophy and decreased vision. Visual loss from sphenoid sinus mucoceles is usually associated with a poor prognosis if surgical treatment is delayed more than seven to ten days.  相似文献   
70.
We examined the effect of HemoHIM on the protective efficacy of hematopoietic stem cells and on the recovery of immune cells against sublethal doses of ionizing radiation. Two‐month‐old mice were exposed to γ‐rays at a dose of 8, 6.5, or 5 Gy for a30‐day survival study, endogenous spleen colony formation, or other experiments, respectively. HemoHIM was injected intraperitoneally before and after irradiation. Our results showed that HemoHIM significantly decreased the mortality of sublethally irradiated mice. The HemoHIM administration decreased the apoptosis of bone marrow cells in irradiated mice. On the other hand, HemoHIM increased the formation of endogenous spleen colony in irradiated mice. In irradiated mice, the recovery of total leukocytes in the peripheral blood and lymphocytes in the spleen were enhanced significantly by HemoHIM. Moreover, the function of B cells, T cells, and NK cells regenerated in irradiated mice were significantly improved by the administration of HemoHIM. HemoHIM showed an ideal radioprotector for protecting hematopoietic stem cells and for accelerating the recovery of immune cells. We propose HemoHIM as a beneficial supplement drug during radiotherapy to alleviate adverse radiation‐induced effects for cancer patients. Copyright © 2013 John Wiley & Sons, Ltd.  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