全文获取类型
收费全文 | 75651篇 |
免费 | 6832篇 |
国内免费 | 5156篇 |
专业分类
耳鼻咽喉 | 774篇 |
儿科学 | 965篇 |
妇产科学 | 809篇 |
基础医学 | 7973篇 |
口腔科学 | 1324篇 |
临床医学 | 9126篇 |
内科学 | 10549篇 |
皮肤病学 | 753篇 |
神经病学 | 3980篇 |
特种医学 | 3148篇 |
外国民族医学 | 26篇 |
外科学 | 8838篇 |
综合类 | 14009篇 |
现状与发展 | 26篇 |
一般理论 | 8篇 |
预防医学 | 5932篇 |
眼科学 | 1461篇 |
药学 | 7795篇 |
71篇 | |
中国医学 | 4761篇 |
肿瘤学 | 5311篇 |
出版年
2024年 | 284篇 |
2023年 | 1070篇 |
2022年 | 2765篇 |
2021年 | 3712篇 |
2020年 | 2859篇 |
2019年 | 2327篇 |
2018年 | 2375篇 |
2017年 | 2371篇 |
2016年 | 2137篇 |
2015年 | 3464篇 |
2014年 | 4300篇 |
2013年 | 4454篇 |
2012年 | 6470篇 |
2011年 | 6751篇 |
2010年 | 4876篇 |
2009年 | 3930篇 |
2008年 | 4798篇 |
2007年 | 4372篇 |
2006年 | 4081篇 |
2005年 | 3710篇 |
2004年 | 2706篇 |
2003年 | 2564篇 |
2002年 | 1984篇 |
2001年 | 1368篇 |
2000年 | 1284篇 |
1999年 | 1080篇 |
1998年 | 665篇 |
1997年 | 602篇 |
1996年 | 532篇 |
1995年 | 509篇 |
1994年 | 422篇 |
1993年 | 291篇 |
1992年 | 322篇 |
1991年 | 299篇 |
1990年 | 248篇 |
1989年 | 196篇 |
1988年 | 183篇 |
1987年 | 154篇 |
1986年 | 145篇 |
1985年 | 119篇 |
1984年 | 110篇 |
1983年 | 79篇 |
1982年 | 63篇 |
1981年 | 60篇 |
1980年 | 56篇 |
1979年 | 55篇 |
1978年 | 50篇 |
1977年 | 39篇 |
1975年 | 41篇 |
1974年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
通过响应面分析的方法对发酵生产γ 氨基丁酸(GABA)的培养基进行优化.利用二水平正交试验考察葡萄糖、豆饼粉、玉米浆、K2HPO4、吐温 80、起始pH值和谷氨酸钠(MSG)对发酵生产GABA的影响.利用极差分析找出主要影响因子:分别为豆饼粉、玉米浆和葡萄糖.利用中心组合设计与响应面分析进一步考察主要影响因子并确定了最佳培养基的组成.在优化培养基中,GABA产量增加约4倍,达到3.63g/L,实验值与预测值基本相符. 相似文献
52.
Lei Ding Christopher Wilke Bobby Xu Xiaoliang Xu Wim van Drongelen Michael Kohrman Bin He 《Journal of clinical neurophysiology》2007,24(2):130-136
SUMMARY: It is desirable to estimate epileptogenic zones with both location and extent information from noninvasive EEG. In the present study, the authors use a subspace source localization method (FINE), combined with a local thresholding technique, to achieve such tasks. The performance of this method was evaluated in interictal spikes from three pediatric patients with medically intractable partial epilepsy. The thresholded subspace correlation, which is obtained from FINE scanning, is a favorable marker, which implies the extents of current sources associated with epileptic activities. The findings were validated by comparing the results with invasive electrocorticographic (ECoG) recordings of interictal spike activity. The surgical resections in these three patients correlated well with the epileptogenic zones identified from both EEG sources and ECoG potential distributions. The value of the proposed noninvasive technique for estimating epileptiform activity was supported by satisfactory surgery outcomes. 相似文献
53.
目的探讨经尿道等离子双极电切术(PKRP)治疗良性前列腺增生(BPH)术后对阴茎勃起功能的影响。方法PKRP、经尿道前列腺电切术(TURP)治疗BPH各95例,评价其术后1个月、3个月及1年阴茎勃起功能。结果PKRP、TURP术后1个月、3个月及1年阴茎勃起功能障碍(ED)发生率分别是3.2%、2.1%、2.1%和13.7%、10.5%、9.5%。结论PKRP术后ED发生率比TURP低,是一种对阴茎勃起功能较为安全的治疗良性前列腺增生的方法。 相似文献
54.
F A Rustamov A M Kazenkov N N Smirnova N V Bo?kova K M Sergeeva M N Maslova 《Patologicheskaia fiziologiia i èksperimental'naia terapiia》1991,(5):37-39
The authors undertook comparative study of the Na, K-ATPase activity in the red cells, ghost corpuscles, and in the cortex and medulla of kidneys of rats with experimental glomerulonephritis (GN) induced by injection of nephrotoxic serum (NTS), during an acute course of the process (1 and 2 weeks after NTS injection) and in chronic affection of the kidneys (10 weeks after NTS injection). The activity of the enzyme both in the red cells and in the ghost corpuscles was reduced significantly, by 28 and 22%, respectively, in the acute period of the disease (one week after NTS injection) but was restored to normal values in the period of chronic affection of the kidneys. The activity of the enzyme did not change in the cortex during the whole period of the study, but in the medulla it diminished in the acute period of the disease and remained reduced (by 27% on the average) during the chronic phase. It is concluded that reduction of the enzyme activity in the studied objects was not caused by the presence of endogenous inhibitors of the enzyme. It is suggested that reduction of Na, K-ATPase activity in the renal medulla may be one of the factors of increase of Na and water excretion in the urine in the chronic phase of GN. 相似文献
55.
Peter Wallstr?m Krystyna Frenkel Elisabet Wirf?lt Bo Gullberg Jerzy Karkoszka Janeric Seideg?rd Lars Janzon G?ran Berglund 《Cancer epidemiology, biomarkers & prevention》2003,12(5):444-451
Plasma autoantibodies (aAbs) against the oxidized DNA base derivative 5-hydroxymethyl-2'-deoxyuridine (5-HMdU) are potential biomarkers of cancer risk and oxidative stress. We examined their association with a number of cancer risk factors: smoking, alcohol habits, body fatness, and absence of the glutathione S-transferases M1 and T1 (GSTM1 and GSTT1) in a sample from the population-based Malm? Diet and Cancer cohort (Sweden). This was a cross-sectional study of 264 men and 280 women, 46-67 years of age. Anti-5-HMdU aAb concentration was determined by an ELISA. Data on tobacco exposure were collected through a questionnaire. Alcohol consumption was estimated by a modified diet history method. Body fatness was assessed by a bioimpedance method. The absence or presence of genes coding for GSTM1 and GSTT1 was determined in granulocyte DNA by a multiplex PCR technique. aAb titers were significantly greater in those with high alcohol consumption. Current smokers lacking GSTM1, particularly men, had greater aAb titers compared with nonsmokers or persons expressing GSTM1. Body fatness was inversely associated with antibody titers in men. GSTT1 genotype was not associated with aAb titers. Overall, women had higher aAb titers than men. Adjustment for potential confounders (history of chronic diseases, anti-inflammatory medication, and season of blood sampling) did not change the results. Our study shows that a high alcohol consumption, smoking in combination with lack of GSTM1, and low body fatness (in men) is associated with high titers of anti-5-HMdU aAbs in this population. 相似文献
56.
目的 研究糖尿病膀胱病变(Diabetic cystopathy,DCP)储尿期尿动力学特征及膀胱感觉功能障碍,为阐明DCP的发病机制提供实验依据。方法 分别以链脲佐菌素(STZ)、蔗糖诱导制作大鼠DCP模型及利尿模型,正常大鼠作对照。采用免疫组化结合图像分析技术观察膀胱感觉神经递质CGRP及其纤维改变;制备离体全膀胱,作膀胱灌注测压观察膀胱顺应性改变;放免法测定逼尿肌舒张信号转导分子cAMP。结果 DCP8周时,膀胱壁尤其是粘膜下层的CGRP及其神经纤维明显减少;离体膀胱测压显示糖尿病膀胱顺应性升高;膀胱舒张作用明显弱于对照组和利尿组,逼尿肌cAMP含量显著低于后者。结论 ①DCP对膀胱功能的损害是多方面的:CGRP为主要递质的粘膜下层膀胱容量感觉纤维明显减少,膀胱顺应性改变是DCP的致病机制之一。②DCP早期即已发生储尿期功能障碍,并且可能是膀胱收缩功能损伤的因素。③非糖尿病性利尿状态(多尿)对膀胱功能构成一定的损害作用,但不是DCP形成的主要原因。提示临床上对糖尿病患者作必要的尿动力学检查能较早发现DCP,有助于保护膀胱功能。 相似文献
57.
脑血管意外尿失禁的机制探讨 总被引:4,自引:0,他引:4
目的探讨脑血管意外引起尿失禁的可能机制。方法对42例诊断为脑血管意外伴有尿失禁的患者进行尿动力学检查(包括静止期尿道压测定、充盈期及排尿期膀胱尿道功能测定)并按Burney分类进行分析,同时研究病变部位、脑血管意外性质和病变半球侧与尿动力学的关系。结果42例脑血管意外患者中,表现为逼尿肌反射亢进者31例(73.8%):其中外括约肌无抑制性松弛19例(45.2%),逼尿肌-外括约肌不协调3例(7.1%),逼尿肌-外括约肌协调9例(21.4%);逼尿肌反射减低,外括约肌协调者11例(26.2%);无逼尿肌功能正常者。发生膀胱顺应性减低5例(11.9%),发生尿感缺失者11例(26.2%)。初感尿容量(140.00±46.97)ml;膀胱最大容量(293.20±60.71)ml;最大尿道闭合压(65.14±19.83)cmH2O。逼尿肌最大收缩力(Pdetmax)为(60.98±31.11)cmH2O;最大尿流率时逼尿肌压力(Pdet-Qmax)为(35.98±17.46)cmH2O;逼尿肌收缩时间(Tcon)为(86.07±36.09)sec;最大流量(Qmax)为(9.02±5.62)ml/s。中风后尿失禁患者其发病部位多见于基底节、皮层多灶以及额顶叶,脑出血与脑梗塞患者的尿动力学表现无明显差异,左右半球病变对尿动力学也无明显差异。结论脑血管意外后尿失禁的尿动力学异常主要为逼尿肌反射亢进,部分出现逼尿肌反射减弱,但感觉正常,感觉缺失者较少见;外括约肌功能以无抑制性松弛为主,其次为逼尿肌-外括约肌协调,少数出现不协调;较少出现膀胱顺应性降低。 相似文献
58.
膀胱癌中环氧化酶-2的表达与临床病理的关系(英文) 总被引:4,自引:2,他引:2
目的 探讨环氧化酶 - 2 (COX - 2 )表达与膀胱癌生物学行为的关系及其意义。方法 采用免疫组化SABC法检测 5 4例膀胱癌、2 9例癌旁组织和 10例正常膀胱粘膜中的COX - 2表达 ,结合临床病理资料进行分析。结果 COX - 2在不同膀胱组织中的表达差异有显著性 (P <0 .0 5 ) ,即膀胱癌组织 >癌旁组织 >正常膀胱粘膜。COX - 2表达随膀胱癌病理级和临床分期的增加而增加 (P <0 .0 5、P <0 .0 1) ,且癌组织中COX - 2表达与淋巴转移有关 (P <0 .0 5 )。结论 COX - 2表达与膀胱癌病理分级、临床分期、淋巴转移有关 ,提示它可能在胱癌的发生、发展中扮演重要角色 ,通过抑制COX - 2活性可能为膀胱癌的防治提供新途径。 相似文献
59.
60.