全文获取类型
收费全文 | 38576篇 |
免费 | 3075篇 |
国内免费 | 954篇 |
专业分类
耳鼻咽喉 | 320篇 |
儿科学 | 1429篇 |
妇产科学 | 826篇 |
基础医学 | 2108篇 |
口腔科学 | 924篇 |
临床医学 | 4380篇 |
内科学 | 7117篇 |
皮肤病学 | 480篇 |
神经病学 | 2209篇 |
特种医学 | 1285篇 |
外国民族医学 | 1篇 |
外科学 | 3413篇 |
综合类 | 5449篇 |
现状与发展 | 1篇 |
预防医学 | 5002篇 |
眼科学 | 1849篇 |
药学 | 2892篇 |
39篇 | |
中国医学 | 1519篇 |
肿瘤学 | 1362篇 |
出版年
2024年 | 184篇 |
2023年 | 991篇 |
2022年 | 1916篇 |
2021年 | 2468篇 |
2020年 | 2126篇 |
2019年 | 1905篇 |
2018年 | 1911篇 |
2017年 | 1480篇 |
2016年 | 1428篇 |
2015年 | 1325篇 |
2014年 | 2729篇 |
2013年 | 2722篇 |
2012年 | 2229篇 |
2011年 | 2408篇 |
2010年 | 1934篇 |
2009年 | 1855篇 |
2008年 | 1795篇 |
2007年 | 1808篇 |
2006年 | 1402篇 |
2005年 | 1274篇 |
2004年 | 956篇 |
2003年 | 819篇 |
2002年 | 578篇 |
2001年 | 563篇 |
2000年 | 421篇 |
1999年 | 411篇 |
1998年 | 313篇 |
1997年 | 297篇 |
1996年 | 248篇 |
1995年 | 249篇 |
1994年 | 231篇 |
1993年 | 171篇 |
1992年 | 191篇 |
1991年 | 156篇 |
1990年 | 127篇 |
1989年 | 118篇 |
1988年 | 98篇 |
1987年 | 96篇 |
1986年 | 70篇 |
1985年 | 109篇 |
1984年 | 102篇 |
1983年 | 63篇 |
1982年 | 67篇 |
1981年 | 57篇 |
1980年 | 49篇 |
1979年 | 30篇 |
1978年 | 42篇 |
1977年 | 26篇 |
1976年 | 20篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
目的:观察丙氨瑞林对子宫内膜癌的治疗作用。方法:对诊刮确诊的17例子宫内膜癌病人,予丙氨瑞林700μg,im,qd×7d,用药前后作性激素测定及组织学检查。结果:绝经妇女用药后血中FSH和LH下降(P<0.01和<0.05),雌二醇、孕酮及睾丸酮变化不明显。其中13例内膜样腺癌用药后有丝分裂指数明显下降(P<0.01),有丝分裂指数变化与癌周内膜之反应有关。呈增生反应癌周内膜癌组织有丝分裂指数下降值明显高于呈萎缩状态癌周内膜。结论:丙氨瑞林治疗子宫内膜癌后能降低FSH和LH水平,对子宫内膜癌尤其是雌激素依赖性内膜癌有一定疗效。 相似文献
92.
To provide better transient performance in controlling robots, a mixed minimum time and quadratic performance index is used. For known and uncertain revolute robot manipulators a conventional optimal control and a robust guaranteed cost control are proposed respectively. Asymptotic stability is also discussed based on the Lyapunov direct method. The proposed robust control is continuous and requires no knowledge of the uncertain system except for bounding functions. 相似文献
93.
羧酸酯酶和羧酸酯酶基因表达量与体质量指数的关系及其基因多态性分析 《首都医科大学学报》2023,44(1):13-19
目的 通过检测健康志愿者的羧酸酯酶1 (carboxylesterase 1,CES1)和羧酸酯酶2 (carboxylesterase 2,CES2)的基因多态性和基因表达水平,探索CES1和CES2在代谢中的作用。方法 从48例健康志愿者获得血样并提取DNA,对DNA进行二代基因测序,并提取总RNA检测基因表达量。使用多元线性回归分析CES1和CES2基因表达量与性别、年龄、体质量指数(body mass index, BMI)的关系。结果 CES1的基因表达量为141.8(72.7,237.8),CES2的基因表达量为74.4(30.8,133.6)。多元线性回归分析中,BMI与CES2的基因表达有关,性别、年龄和BMI与CES1的基因表达无关。发现CES1 20个基因变异,其中10个会引起氨基酸序列改变;发现CES2 6个基因变异,其中2个引起氨基酸序列改变。结论 发现CES2的表达水平与BMI相关,CES1的表达水平与BMI无明显相关,基因预测结果提示CES1的遗传变异可能影响其功能表达。 相似文献
94.
背景 我国人口老龄化形势日益严重,家庭医生签约服务对助推分级诊疗制度建设、建立合理有序就医秩序发挥着重要作用,目前学者对家庭医生签约服务政策的研究主要集中于定性评价,较少有学者利用工具聚焦代表性政策对各篇进行定量评价。目的 定量评价我国中央层面的6篇家庭医生签约服务相关政策,分析政策优劣,在此基础上,提出促进我国家庭医生签约服务高质量发展的对策和措施,助力健康中国战略实施。方法 于2022-04-30,以“家庭医生”为关键词在北大法宝数据库进行全文检索,并在国务院网站进行相关内容检索,检索时限为2015-01-01至今。采用ROSTCM 6.0软件进行文本挖掘,然后以其结果为依据选择其中具有代表性的中央层面家庭医生签约服务相关政策,并基于政策一致性评价(PMC)指数模型对其进行量化评价。结果 依据纳入与排除标准检索获得相关政策32篇,家庭医生签约服务领域排名前5位的高频关键词为“签约服务”(274次)、“健康”(272次)、“医疗”(264次)、“家庭医生”(225次)、“签约”(180次),以其为依据共选择中央层面有代表性的家庭医生签约服务相关政策6篇,分别标记为P1~P6。政策量化... 相似文献
95.
T. I. Shklyar 《Bulletin of experimental biology and medicine》1977,84(5):1631-1632
Wounds 1 cm long, down to the cutaneous muscle, were inflicted on rats aged 11 days, 2 months, and 2.5 months in the subscapular region. Nociceptive stimulation was applied to the animals by means of an electric current 48 h after the operation. Mitotic activity was determined in cells of the stratum basale of the skin epithelium adjacent to the wound. Nociceptive stimulation was found to reduce the mitotic index of the cutaneous epithelial cells of the animals of all age groups studied by a considerable degree (by several times). An increase in the mitotic index was observed from the early to the later stages of postnatal ontogeny.Laboratory of Age and Evolutionary Physiology, Voroshilovgrad Pedagogic Institute. Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 11, pp. 605–606, November, 1977. 相似文献
96.
光化学诱导的血栓形成性脑缺血及其代谢改变 总被引:4,自引:2,他引:4
本文用光化学法激发大鼠局部脑血栓形成,以组织病理学、局部脑血流量、皮层水含量、三磷酸腺苷、二磷酸腺苷,一磷酸腺苷、能量负荷、肌酸及乳酸为指标,探讨局部脑血栓形成后5天rCBF明显增高的可能机理。结果表明,血栓形成后局部脑组织ATP水平进行性减少(P<0.01)、ADP/ATP及AMP/ATP比值明显升高(P均<0.01),LA及脑水含量显著增加(P<0.01)。这些因素既是能量衰竭、无氧酵解的结果 相似文献
97.
Ishiguro N Kanehisa H Miyatani M Masuo Y Fukunaga T 《European journal of applied physiology》2005,94(1-2):25-35
This study tested the hypothesis that, as compared to whole-body bioelectrical impedance (BI) analysis, segmental BI analysis can estimate lean body mass (LBM) more accurately in a population with a large difference in muscularity. In addition to whole-body BI, which determines impedance (Z) between the wrist and ankle, two segmental BI analyses which determine the Z value of every body segment in each of (1) the arms, legs and trunk (distal BI) and (2) the upper arms, upper legs and trunk (proximal BI) were applied to a group of 125 male athletes and 75 non-athletes. The subjects were divided into validation and cross-validation groups. Simple and multiple regression analyses were applied to (length)2/Z (BI index) values for the whole-body and each body segment, to develop the prediction equations of LBM measured using air-displacement plethysmography. In the validation group, the SE of estimation was similar in the whole-body (3.4 kg, 5.4%), distal (3.4 kg, 5.5%) and proximal BI (3.3 kg, 5.2%) analyses. However, the whole-body and distal BI analyses produced systematical errors in the estimates of LBM. Moreover, the residuals in the two methods significantly (P<0.05) correlated with the ratios of BI indices of the upper arms and upper legs to those of the arms and legs, respectively, calculated as variables approximating the relative development of lean tissues at the proximal area of limbs. On the other hand, the proximal BI analysis was validated and cross-validated. Thus, the accuracy of estimating LBM was similar in the whole-body and the two segmental BI analyses. However, the prediction equations derived from the use of the whole-body BI index and a combination of the arms, legs and trunk BI indices produced a systematical error relating to the difference between the limb segments in lean tissue development. 相似文献
98.
Zheng-Lin Jiang Hisao Yamaguchi Akira Takahashi Shingo Tanabe Noboru Utsuyama Toshitaka Ikehara Keiko Hosokawa Hiroyuki Tanaka Yohsuke Kinouchi Hiroshi Miyamoto 《European journal of applied physiology》1995,70(3):234-239
Cerebral blood volume flow and flow velocity have been reported to increase during dynamic exercise, but whether the two increase in parallel and whether both increases occur as functions of exercise intensity remain unsettled. In this study, blood flow velocity in the common carotid artery was measured using the Doppler ultrasound method in eight healthy male students during graded treadmill exercise. The exercise consisted of stepwise progressive increases and decreases in exercise intensity. The peak intensity corresponded to approximately 85% of maximal oxygen consumption. During this exercise, the heart rate (f
c), mean blood pressure (BP) in the brachial artery and mean blood flow velocity (cc) in the common carotid artery increased as functions of exercise intensity. At the peak exercise intensity, (f
c), BP and cc increased by 134.5%, 20.5% and 51.8% over the control levels before exercise (P < 0.01), respectively. The resistance index (RI) and pulsatility index (PI) were determined from the velocity profile and were expected to reflect the distal cerebral blood flow resistance. The RI and PI increased during the graded exercise, but tended to decrease at the highest levels of exercise intensity. As cc increased with increases in exercise intensity it would be expected that cerebral blood flow would also increase at these higher intensities. It is also suggested that blood flow velocity in the cerebral artery does not proportionately reflect the cerebral blood flow during dynamic exercise, since the cerebral blood flow resistance changes. 相似文献
99.
Kiyohisa Sekizawa MDa Hideki Nakazawa MDa Masatoshi Morikawa MDa Kohei Yamauchi MDb Kazutaka Maeyama MDc Takehiko Watanabe MDc Hidetada Sasaki MDa 《The Journal of allergy and clinical immunology》1995,96(6)
Background: Histamine N-methyltransferase (HMT) modulates histamine- and antigen-induced bronchoconstriction. However, it is unclear whether vascular permeability evoked by an allergic reaction can be exaggerated by inhibition of HMT activity. Methods: We studied the effects of intravenously injected SKF 91488, a specific HMT inhibitor, on increases in plasma extravasation induced by intravenously injected histamine in unsensitized guinea pigs and by intravenously injected ovalbumin antigen in guinea pigs sensitized to ovalbumin in vivo with Evans blue dye as a marker. Results: Pretreatment with SKF 91488 shifted, in a dose-dependent fashion, the dose-response curves of the leakage of dye to histamine to lower concentrations in the trachea, main bronchi, and nasal mucosa. Likewise, pretreatment with SKF 91488 (20 mg/kg intravenously) significantly increased the leakage of dye induced by ovalbumin antigen (200 μg/kg intravenously) in three parts of the airway (p < 0.05). In contrast to SKF 91488, intravenously injected aminoguanidine, a specific inhibitor of diamine oxidase (16 mg/kg intravenously), did not alter the leakage of dye induced by histamine (from 0.001 μg/kg to 10 μg/kg intravenously) (p > 0.20). HMT activities were observed in the nasal mucosa, as well as in the trachea and main bronchi, as shown in a previous study. Conclusion: These findings suggest that HMT modulates the effects of exogenous histamine and endogenously released histamine induced by antigen challenge on plasma extravasation in the airway in guinea pigs in vivo. (J ALLERGY CLIN IMMUNOL 1995;96:910-6.) 相似文献
100.