全文获取类型
收费全文 | 524630篇 |
免费 | 33437篇 |
国内免费 | 25208篇 |
专业分类
耳鼻咽喉 | 4398篇 |
儿科学 | 10498篇 |
妇产科学 | 8193篇 |
基础医学 | 58331篇 |
口腔科学 | 7782篇 |
临床医学 | 61551篇 |
内科学 | 82997篇 |
皮肤病学 | 4024篇 |
神经病学 | 35104篇 |
特种医学 | 21845篇 |
外国民族医学 | 220篇 |
外科学 | 63749篇 |
综合类 | 59179篇 |
现状与发展 | 82篇 |
一般理论 | 21篇 |
预防医学 | 40532篇 |
眼科学 | 13041篇 |
药学 | 45674篇 |
382篇 | |
中国医学 | 20511篇 |
肿瘤学 | 45161篇 |
出版年
2024年 | 1190篇 |
2023年 | 5579篇 |
2022年 | 14586篇 |
2021年 | 18257篇 |
2020年 | 13649篇 |
2019年 | 11902篇 |
2018年 | 33188篇 |
2017年 | 27588篇 |
2016年 | 29020篇 |
2015年 | 16791篇 |
2014年 | 20437篇 |
2013年 | 18050篇 |
2012年 | 32230篇 |
2011年 | 48751篇 |
2010年 | 36019篇 |
2009年 | 25108篇 |
2008年 | 37745篇 |
2007年 | 39971篇 |
2006年 | 19175篇 |
2005年 | 20333篇 |
2004年 | 14835篇 |
2003年 | 14821篇 |
2002年 | 11502篇 |
2001年 | 8310篇 |
2000年 | 9213篇 |
1999年 | 9739篇 |
1998年 | 5987篇 |
1997年 | 6018篇 |
1996年 | 4640篇 |
1995年 | 4269篇 |
1994年 | 3499篇 |
1993年 | 2258篇 |
1992年 | 2983篇 |
1991年 | 2655篇 |
1990年 | 2348篇 |
1989年 | 2031篇 |
1988年 | 1681篇 |
1987年 | 1456篇 |
1986年 | 1188篇 |
1985年 | 979篇 |
1984年 | 572篇 |
1983年 | 413篇 |
1982年 | 280篇 |
1981年 | 246篇 |
1980年 | 233篇 |
1979年 | 235篇 |
1978年 | 91篇 |
1977年 | 92篇 |
1974年 | 121篇 |
1973年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of hexoestrol (HES) was developed, optimized and validated for the analysis of HES in pork. Many parameters, such as the volume ratio of solution A and solution B, colour developing time, pH value, incubation time, the volume ratio of the standard solution and diluted antiserum, blocking solution, blocking condition, coating solution and coating condition were studied and optimized in the paper. The regression equation of the final inhibition curve is y = - 0.3345x + 1.4955, R2=0.9913. The linear range is 0.1-8.1 ng/ml, and the IC50 is 0.671 ng/ml. The specificity of the assay was evaluated by the cross-reactivity rates of six compounds, of which two structurally related compounds had a relatively higher cross-reactivity rate of 25% and 6%. HES was added into a pork sample at 5 ng/g level and then the sample was extracted. The recovery is between 49.6% and 79.2%, and the variation coefficient is 0.164. 相似文献
62.
近年来,伴随着药物治疗的快速发展.以药理活性非常强的药物为代表,开发出许多用药时必须给予足够关注的药物,“用药最适化”这一概念逐渐成为人们非常关注的问题。这主要是为了实现用药时的最佳形式。尽可能地根据选择或者需要控制药物的浓度.时间模式。输送到药物的作用表达部位。实现治疗用药的安全性。但是,历来的方法却很难实现这一点,通过利用新的技术和方法调控药物在体内的动态变化,以获得最好治疗效果为中心的药物使用方法和药剂正在开发之中。这就是给药系统,使用可以表达自身概念的语言来命名。虽然都是以各种药物在体内的动态过程作为调控对象,但是还分为①controlled release(调控释放给药);②开发新的给药途径、克服药物吸收障碍;③靶向给药(targeting)等三个途径。 相似文献
63.
64.
65.
Tarek A. Amer Tarek F. Elwakil Mahmoud S. Elbasiouny 《European journal of plastic surgery》2007,30(2):67-73
Haemangiomas are the most common tumours of infancy. They typically proliferate then involute with considerable variation
as regards to their rates of proliferation and involution. Haemangioma of the nasal tip is a lesion of special characteristics.
During proliferation, it expands, contracts and deviates the nasal cartilages. Particularly, it regresses slowly and frequently
involutes incompletely. That is why excision of the lesion is frequently suggested. The present study was conducted to evaluate
open rhinoplasty after initial non-excision treatment modalities namely, intra-lesional corticosteroid injections and laser
treatment, as a protocol of treatment for nasal tip haemangiomas. Twelve patients with nasal tip haemangiomas were included
in the present study. Patients of both sexes, of different ages, with deep and mixed haemangiomas were studied. Disfigurement
was the constant presenting symptom. Initial non-excision treatment reported different responses as denoted by the regression
of the lesions’ size. Haemangiomas constantly extended between the medial crura of the alar cartilages as noted by the constant
widening of the columella pre-operatively and the obvious separation of the nasal cartilages intra-operatively. This separation
was constantly found to require approximation by sutures. The results of the present study concluded that whenever an early
presentation with nasal tip haemangioma could be established, initial non-excision treatment followed by open rhinoplasty
could be a useful protocol of treatment. Within the limitations of the present study, this protocol could achieve an early,
safe and effective treatment for nasal tip haemangiomas with provisionally acceptable cosmetic outcomes so far. 相似文献
66.
This study investigates whether tissue recoil or patient intrinsic factors influence the final position of the nipple areola
complex (NAC) after reduction mammoplasty.
The age, pre-operative ptosis, BMI and weight of the tissue resected were recorded as patient intrinsic factors in 37 patients
undergoing reduction mammoplasty. The “spring-back” value was defined as the distance from the sternal notch to a nipple landmark
on the breast meridian with the patient sitting up, minus the same measurement repeated with the patient recumbent to eliminate
the pull of gravity on the breast. Spring back was measured pre-operatively for the nipple and nipple mark then post-operative
for the nipple. The difference in centimeters between the final post-operative distance from the sternal notch to the nipple
and the level intended by the pre-operative nipple mark was termed the “judgment error.” The final position of the post-operative
nipple and the judgment error was compared to the spring-back values and patient intrinsic factors.
Pre-operative ptosis was statistically related to increasing patient BMI and mass of tissue resected per breast. Pre-operative
spring-back values for the nipple increased with increasing ptosis, BMI and decreasing age. Spring-back values were greater
in the lower pole of the breast than in the upper pole. The final position of the nipple was higher than the pre-operative
mark in 65% of cases, lower in 8% and as marked in 27% of cases. The post-operative NAC was, on average, 0.6 cm higher than
planned pre-operatively. The post-operative distance from the sternal notch to the nipple increased with increasing pre-operative
ptosis, mass of breast tissue resected per breast and all three spring-back values. The difference between the level of the
pre-operative mark and the final nipple position showed a weak correlation with post-operative spring-back values.
The parameters of ptosis, BMI, weight of tissue resected per breast and pre-operative nipple spring back reflect body habitus
and breast size. Spring-back values vary between the upper and lower pole of the breast. The final NAC position was higher
than that intended at pre-operative marking in the majority of cases. The surgeon instinctively marks the nipple lower in
patients with greater pre-operative ptosis and in whom a larger resection is anticipated. Judgment error did not relate to
intrinsic factors nor to pre-operative spring-back values; hence, these parameters cannot be applied as predictive tools for
more accurate pre-operative marking of the nipple position. This study suggests that the pre-operative nipple mark should
be placed, with the patient sitting up, at least 23 cm from the sternal notch and 0.6 cm lower than the final position estimated
using the inframammary crease as a landmark.
An invited commentary on this paper is available at . 相似文献
67.
68.
Jamshid Shirani Jagat Narula William C. Eckelman Navneet Narula Vasken Dilsizian 《Journal of nuclear cardiology》2007,14(1):100-110
Conclusions Noninvasive imaging of neurohumoral upregulation in remodeled myocardium suggests that an imaging strategy can be developed
for predicting the rate of remodeling and likelihood of HF development. This should allow a more judicious use of neurohumoral
antagonists especially in subjects who do not have manifest HF.74 In others specific targeted imaging may allow timely selection of individualized treatment strategies and ensure optimization
of therapeutic intervention. Similar to ACE and AII receptors, multiple other targets in the hormonal cascades can identify
the likelihood of adverse and favorable remodeling.74 相似文献
69.
Huimin Wang Changyuan Wang Jihong Yao Kexin Liu 《Blood coagulation & fibrinolysis》2007,18(6):555-558
Fully soluble hemostatic fiber (FHF) is made from cotton yarn through a series of chemical reactions with NaOH and chloroacetic acid. The major component of FHF is carboxymethylcellulose. FHF is a kind of biodegradation macromolecule material that can disassociate into a low-molecular-weight compound or a simple substance by hydrolytic and enzymatic courses. The purpose of the present study is to investigate the hemostatic mechanism of FHF. The study indicated that FHF can stop bleeding by physical, chemical and physiological routes. In the physical route, expansion of carboxymethylcellulose in FHF stops bleeding by forming a mechanical clog after contacting with the blood. In the chemical route, the platelets can quickly aggregate around FHF and stimulate releasing and disaggregating reactions, after contacting with the rough surface of FHF, producing thrombus and hemostasis. In the physiological route, gluey particles with negative charges can activate intrinsic coagulation systems by activating the blood coagulation factor XII after FHF dissolution. 相似文献
70.