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101.
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103.
The Vpr protein of human immunodeficiency virus type 1 influences nuclear localization of viral nucleic acids in nondividing host cells. 总被引:32,自引:3,他引:32 下载免费PDF全文
104.
Argininosuccinate synthetase: essential role of cysteine and arginine residues in relation to structure and mechanism of ATP activation. 下载免费PDF全文
S Kumar J Lennane S Ratner 《Proceedings of the National Academy of Sciences of the United States of America》1985,82(20):6745-6749
We have undertaken studies to identify amino acid residues that are involved in the catalytic mechanism of argininosuccinate synthetase [L-citrulline:L-aspartate ligase (AMP-forming), EC 6.3.4.5] and have found that a cysteine residue and an arginine residue are required for activity. The reactive cysteine residues are accessible to solvent and available to react with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Four cysteine residues, one per subunit, are shown by enzymatic assay to be required for catalytic activity, suggesting that a reactive cysteine lies within the active site of argininosuccinate synthetase. In the presence of sodium dodecyl sulfate, 12 cysteine residues react with DTNB; consequently, all of the half-cystine residues in the native enzyme are present in the reduced sulfhydryl form. We also present evidence for the participation of arginine groups in the binding of ATP and PPi. Modification of argininosuccinate synthetase with [14C]-phenylglyoxal results in incorporation concomitant with loss of catalytic activity of 4 mol of phenylglyoxal per mol of native enzyme (one arginine per active site). ATP and PPi protect the enzyme from phenylglyoxal incorporation. Based on these results, we propose that the essential arginine in the active site participates in the binding of ATP and PPi. The binding of ATP and PPi at the same site is mutually exclusive; this exclusion is in accord with the finding that argininosuccinate synthetase has one reactive arginine residue per active site per subunit. This is consistent with our previously proposed reaction mechanism. 相似文献
105.
A high frequency of nonhemolytic hereditary ovalocytosis in Malayan aborigines is thought to result from reduced susceptibility of affected individuals to malaria. Indeed, Kidson et al. recently showed that ovalocytes from Melanesians in Papua New Guinea are resistant to infection in culture by the malarial parasite Plasmodium falciparum. In order to determine if protection against parasitic invasion in these ovalocytes might be the result of some altered membrane material property in these unusual cells, we measured their membrane and cellular deformability characteristics using an ektacytometer . Ovalocytic red cells were found to be much less deformable in comparison to normal discoid red cells. Similar measurements on isolated membrane preparations revealed a marked reduction in ovalocytic membrane deformability. To produce equal deformation of ovalocytic and normal membranes, ovalocytes required an 8-10-fold increase in applied shear stress, indicating that their membrane was capable of deforming under sufficient stress. To test the possibility that this increased membrane rigidity might confer resistance to parasitic invasion, we performed an in vitro invasion assay using Plasmodium falciparum merozoites and Malayan ovalocytes of varying deformability from seven different donors. The level of infection of the ovalocytes ranged from 1% to 35% of that in control cells, and the extent of inhibition appeared to be closely related to the reduction in membrane deformability. Moreover, we were able to induce similar resistance to parasitic invasion in nonovalocytic normal red cells by increasing their membrane rigidity with graded exposure to a protein crosslinking agent. Our findings suggest that resistance to parasite invasion of Malayan ovalocytes is the result of a genetic mutation that causes increased membrane rigidity. 相似文献
106.
Timothy R. Sampson Brooke A. Napier Max R. Schroeder Rogier Louwen Jinshi Zhao Chui-Yoke Chin Hannah K. Ratner Anna C. Llewellyn Crystal L. Jones Hamed Laroui Didier Merlin Pei Zhou Hubert P. Endtz David S. Weiss 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(30):11163-11168
107.
丁同领|赵新|肖朝辉|余灵祥|乐羿|洪智贤|张绍庚| 《中国普通外科杂志》2014,23(1):22-27
目的:分析丙肝相关性肝癌(HCV-HCC)根治术后复发规律及相关危险因素,探讨针对复发时相的个体化临床干预。 方法:回顾98例行HCV-HCC根治术的患者临床病理资料,分析患者根治术后复发规律,对复发的可能影响因素进行单因素及多因素分析,并对病毒因素进行分层分析。 结果:全组根治术后有2个复发高峰,以24个月为界分为早、晚期;COX比例风险模型分析显示,肿瘤低分化、镜下微血管侵犯为术后早期复发的独立危险因素(P<0.001),病毒载量为晚期复发的独立危险因素(P=0.013);术后病毒载量持续阴性患者无瘤生存期明显长于术后持续高病毒载量或病毒载量不稳定者(P<0.001)。 结论:HCV-HCC根治术后早、晚期复发影响因素不同;早期复发率较高,预防性TACE可改善早期复发高危者预后;术后抗病毒治疗可改善远期疗效。
相似文献108.
目的:探讨CD 44V 6、E-cadherin和nm 23-H 1蛋白表达与子宫颈癌的发生、发展及转移的关系。方法:采用免疫组化SP法检测50例子宫颈癌组织和10例正常子宫颈组织中CD 44v6、E-cadherin和nm 23-H 1蛋白的表达情况。结果:CD 44v6蛋白在子宫颈癌组织中的阳性率为66%,CD 44v6高表达与宫颈癌的组织学分级、淋巴结转移呈正相关(P<0.05及P<0.01)。E-cadherin和nm 23-H 1蛋白在宫颈癌组织中阳性表达率分别为62%和48%,显著低于正常宫颈组织(100.0%),P<0.05及P<0.01,但E-cadherin和nm 23-H 1阳性表达与宫颈癌的临床分期、组织学分级、间质浸润和淋巴结转移无关(P>0.05)。宫颈癌中CD 44v6表达与E-cadherin和nm 23-H 1表达呈负相关(P<0.01及P<0.05)。结论:在子宫颈癌中CD 44v6蛋白高表达和E-cadherin、nm 23-H 1蛋白低表达是判断宫颈癌的生物学行为的良好指标。 相似文献
109.
Alexandra L. Coria Tracy L. Rabin Amy R.L. Rule Heather Haq James C. Hudspeth Leah Ratner Ingrid Walker-Descartes 《Journal of general internal medicine》2022,37(1):217
The COVID-19 pandemic plunged hospital systems into resource-deprived conditions unprecedented since the 1918 flu pandemic. It brought forward concerns around ethical management of scarcity, racism and distributive justice, cross-disciplinary collaboration, provider wellness, and other difficult themes. We, a group of medical educators and global health educators and clinicians, use the education literature to argue that experience gained through global health activities has greatly contributed to the effectiveness of the COVID-19 pandemic response in North American institutions. Support for global health educational activities is a valuable component of medical training, as they build skills and perspectives that are critical to responding to a pandemic or other health system cataclysm. We frame our argument as consideration of three questions that required rapid, effective responses in our home institutions during the pandemic: How can our health system function with new limitations on essential resources? How do we work at high intensity and volume, on a new disease, within new and evolving systems, while still providing high-quality, patient-centered care? And, how do we help personnel manage an unprecedented level of morbidity and mortality, disproportionately affecting the poor and marginalized, including moral difficulties of perceived care rationing?KEY WORDS: global health education, global health, medical education, COVID-19 相似文献
110.
Manabu Fujimoto Jun Asai Yoshihide Asano Takayuki Ishii Yohei Iwata Tamihiro Kawakami Masanari Kodera Masatoshi Abe Masahiro Amano Ryuta Ikegami Taiki Isei Zenzo Isogai Takaaki Ito Yuji Inoue Ryokichi Irisawa Masaki Ohtsuka Yoichi Omoto Hiroshi Kato Takafumi Kadono Sakae Kaneko Hiroyuki Kanoh Masakazu Kawaguchi Ryuichi Kukino Takeshi Kono Monji Koga Keisuke Sakai Eiichi Sakurai Yasuko Sarayama Yoichi Shintani Miki Tanioka Hideaki Tanizaki Jun Tsujita Naotaka Doi Takeshi Nakanishi Akira Hashimoto Minoru Hasegawa Masahiro Hayashi Kuninori Hirosaki Hideki Fujita Hiroshi Fujiwara Takeo Maekawa Koma Matsuo Naoki Madokoro Sei-Ichiro Motegi Hiroshi Yatsushiro Osamu Yamasaki Yuichiro Yoshino Andres James LE Pavoux Takao Tachibana Hironobu Ihn Japanese Dermatological Association Guidelines 《The Journal of dermatology》2020,47(10):1071-1109
The Japanese Dermatological Association prepared guidelines focused on the treatment of skin ulcers associated with connective tissue disease/vasculitis practical in clinical settings of dermatological care. Skin ulcers associated with connective tissue diseases or vasculitis occur on the background of a wide variety of diseases including, typically, systemic sclerosis but also systemic lupus erythematosus (SLE), dermatomyositis, rheumatoid arthritis (RA), various vasculitides and antiphospholipid antibody syndrome (APS). Therefore, in preparing the present guidelines, we considered diagnostic/therapeutic approaches appropriate for each of these disorders to be necessary and developed algorithms and clinical questions for systemic sclerosis, SLE, dermatomyositis, RA, vasculitis and APS. 相似文献