全文获取类型
收费全文 | 4990篇 |
免费 | 601篇 |
国内免费 | 76篇 |
专业分类
耳鼻咽喉 | 69篇 |
儿科学 | 157篇 |
妇产科学 | 224篇 |
基础医学 | 688篇 |
口腔科学 | 86篇 |
临床医学 | 652篇 |
内科学 | 1304篇 |
皮肤病学 | 113篇 |
神经病学 | 344篇 |
特种医学 | 405篇 |
外科学 | 472篇 |
综合类 | 76篇 |
预防医学 | 209篇 |
眼科学 | 68篇 |
药学 | 405篇 |
中国医学 | 37篇 |
肿瘤学 | 358篇 |
出版年
2023年 | 26篇 |
2022年 | 49篇 |
2021年 | 138篇 |
2020年 | 105篇 |
2019年 | 161篇 |
2018年 | 164篇 |
2017年 | 129篇 |
2016年 | 162篇 |
2015年 | 178篇 |
2014年 | 181篇 |
2013年 | 284篇 |
2012年 | 298篇 |
2011年 | 255篇 |
2010年 | 241篇 |
2009年 | 217篇 |
2008年 | 241篇 |
2007年 | 257篇 |
2006年 | 218篇 |
2005年 | 203篇 |
2004年 | 168篇 |
2003年 | 135篇 |
2002年 | 136篇 |
2001年 | 105篇 |
2000年 | 115篇 |
1999年 | 105篇 |
1998年 | 97篇 |
1997年 | 107篇 |
1996年 | 124篇 |
1995年 | 81篇 |
1994年 | 69篇 |
1993年 | 77篇 |
1992年 | 74篇 |
1991年 | 54篇 |
1990年 | 52篇 |
1989年 | 76篇 |
1988年 | 77篇 |
1987年 | 63篇 |
1986年 | 60篇 |
1985年 | 65篇 |
1984年 | 30篇 |
1983年 | 30篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1980年 | 24篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 21篇 |
1975年 | 27篇 |
1973年 | 13篇 |
排序方式: 共有5667条查询结果,搜索用时 31 毫秒
31.
Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
32.
BACKGROUND AND PURPOSE: Hysterectomy is among the most frequently performed surgical procedures in developed countries, but few studies from the Asia-Pacific region have assessed the appropriateness of hysterectomy. The purpose of this study was to examine the rate of inappropriate hysterectomy in Taiwan and its association with patient characteristics and indications for the procedure. METHODS: A random sample of hysterectomies for which claims were submitted to the Taiwan Bureau of National Health Insurance from July 1, 1997 to June 30, 1998 was selected. A total of 658 charts were reviewed by an expert panel composed of 5 senior gynecologists. RESULTS: Overall, 74.2% of patients underwent hysterectomy for appropriate reasons, 5.6% for uncertain reasons, and 20.2% for inappropriate reasons. Inappropriate procedures were positively associated with younger age and premenopausal status. Primary indications that accounted for over 25% of inappropriate procedures were chronic pelvic pain (42.9%), abnormal uterine bleeding (37.5%), and endometriosis (27.7%). CONCLUSIONS: This study found a high rate of inappropriate hysterectomy in Taiwan. Gynecologists and physician organizations should take action to improve physician agreement on the use of hysterectomy, especially for indications associated with high rates of inappropriate procedures. 相似文献
33.
Hui-Ching Chuang Chih-Ying Su Seng-Feng Jeng Chih-Yen Chien 《Otolaryngology--head and neck surgery》2007,137(4):632-635
OBJECTIVE: To preserve oral function after buccal cancer resection, a free anterior lateral thigh flap (ALTF) was used to cover the buccal mucosal defect. STUDY DESIGN AND SETTING: Nine patients who underwent primary surgical treatment between June 2005 and September 2006 for buccal cancer were enrolled in this study. An ALTF was used to repair the defect immediately after tumor resection. Oral function, including mouth-opening width, oral intake, and teeth cleaning, were compared pre- and postoperatively. RESULTS: No difference was observed in the mouth-opening width between that preoperatively and three months postoperatively (P = 0.54). The oral intake and teeth cleaning also remained unchanged three months postoperatively. CONCLUSION: Repair of a buccal mucosa defect with a free anterior lateral thigh flap is a good alternative for selected patients who undergo resection of buccal cancer; oral function is likely to be preserved. 相似文献
34.
Chien Yie W. Chien Te-yen Bagdon Robert E. Huang Yih C. Bierman Robert H. 《Pharmaceutical research》1989,6(12):1000-1010
Several transdermal contraceptive device (TCD) formulations were developed to provide a dual-controlled transdermal delivery of levonorgestrel (LN), a potent progestin, and 17-estradiol (E2), a natural estrogen. Using a sensitive HPLC method, the in vitro release and skin permeation profiles of LN and E2 from various TCD formulations were simultaneously characterized in the hydrodynamically well-calibrated Valia–Chien skin permeation cells and both were found to follow zero-order kinetics. The rates of drug release and skin permeation were observed to vary significantly depending upon some formulation parameters. Six-month stability studies were performed on seven formulations at room and elevated temperatures (37 and 45°C), and two (Formulations 4 and 5) were found to be acceptable, based on drug recovery, release rate, and skin permeation rate data. Judging from the 6-month accelerated stability studies, it is projected these two formulations will have shelf-life of at least 2 years. As a result of development of an efficient manufacturing process, Formulation 4 was selected for further evaluation. One-week primary skin irritation evaluation in 6 rabbits indicated that Formulation 4 is nonirritating, and it was thus selected for Phase I clinical bioavailability/dose proportionality studies in 12 healthy female volunteers of child-bearing age. Results of pharmacokinetic and pharmacodynamic analyses demonstrated that it is capable of achieving and maintaining a steady-state serum level of LN throughout the 3-week treatment period by weekly applications of one or two TCD patches (10 or 20 cm2). A dose proportionality was obtained in the serum drug levels, daily dose delivered, and contraception efficacy. An excellent correlation was obtained for the rates of transdermal delivery determined by the in vitro studies using human cadaver skin, the in vivo studies in rabbits, and the clinical studies in living subjects. 相似文献
35.
Chu PH Yeh HI Jung SM Chien LY Cheng NF Wu HH Chu JJ Hsueh C Lee YS 《Virchows Archiv : an international journal of pathology》2004,444(4):383-386
Cardiac hamartomas are very rare and are demarcated masses of enlarged, hypertrophied, mature myocytes and collagen tissue. Cardiac hamartomas are generally circumscribed in the right ventricle or atrium, but not reported in the crista terminalis (CRT). The CRT is crucial in electrophysiology, is related to arrhythmogenesis, and is targeted by radiofrequency catheter procedures. Previous works only described the benign natures of prominent CRT using non-invasive methods. This study describes an unusual cardiac hamartoma originating from the CRT and extending toward the tricuspid valve. Microscopically, this hamartoma comprised dense collagen and adipose tissue, mixed with hypertrophy, but with disarrayed cardiomyocytes. An irregular gap junction, connexin43, was demonstrated in this cardiac hamartoma. 相似文献
36.
A new model for inflammation-induced preterm birth: the role of platelet-activating factor and Toll-like receptor-4 下载免费PDF全文
Elovitz MA Wang Z Chien EK Rychlik DF Phillippe M 《The American journal of pathology》2003,163(5):2103-2111
Preterm birth is a leading cause of neonatal morbidity and mortality. Despite a growing body of evidence correlating inflammation with preterm birth, the signal transduction pathways responsible for the emptying of the uterus in the setting of intrauterine inflammation has not been elucidated. We now report a unique, reproducible mouse model of localized intrauterine inflammation. This model results in 100% preterm delivery with no maternal mortality. Using our model, we also show that platelet-activating factor is a crucial mediator of both inflammation-induced preterm birth and fetal demise. Using C3H/HeJ mice, we demonstrate that toll-like receptor-4 (TLR-4) plays a role in lipopolysaccharide-induced preterm birth but not in inflammation-induced fetal death. Immunohistochemistry studies demonstrate the presence of the platelet-activating factor receptor in both endometrial glands and smooth muscle in uterine tissues. Molecular studies demonstrate the differential expression of platelet-activating factor receptor and TLR-4 in uterine and cervical tissue throughout gestation. Quantitative polymerase chain reaction revealed an up-regulation of TLR-4 in the fundal region of the uterus in response to intrauterine inflammation. The use of this model will increase our understanding of the significant clinical problem of inflammation-induced preterm birth and will elucidate signal transduction pathways involved in an inflammatory state. 相似文献
37.
Schweigart G Chien RD Mergner T 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2002,147(1):89-97
Vestibular functions are known to show some deterioration with age. Vestibular deterioration is often thought to be compensated
for by an increase in neck proprioceptive gain. We studied this presumed compensatory mechanism by measuring psychophysical
responses to vestibular (horizontal canal), neck and combined stimuli in 50 healthy human subjects as a function of age (range
15–76 years). After passive horizontal rotations of head and/or trunk (torso) in complete darkness (dominant frequencies 0.05,
0.1, and 0.4 Hz), subjects readjusted a visual target to its remembered prerotational location in space. (1) Vestibular-only stimulus (whole-body rotation); subjects' responses were shifted towards postrotatory body position, this only slightly at 0.4 Hz and
pronounced at 0.1 and 0.05 Hz. These errors reflect the known physiological drop of vestibular gain at low rotational frequency.
They exhibited a slight but significant increase with age. (2) Neck-only stimulus (trunk rotated, head stationary); the responses showed errors similar to those upon vestibular stimulation (with offset towards
postrotatory trunk position) and this again slightly more with increasing age. (3) Vestibular-neck stimulus combination during head rotation on stationary trunk; the errors were close to zero, independent of stimulus frequency and the subjects'
age. (4) Opposite stimulus combination (trunk rotated in the same direction as the head, but with double amplitude); the errors were clearly enhanced, essentially
reflecting the sum of those with vestibular-only and neck-only stimulation. Taken together, we find a parallel increase in
neck- and vestibular-related errors with age, in seeming contrast to previous studies. We explain our and the previous findings
by a vestibular-neck interaction model in which two different neck signals are involved. One neck signal is used, in combination
with the vestibular signal, for estimating trunk-in-space rotation. It is internally shaped to always match the vestibular
signal, so that these two signals cancel each other out when summed during head rotation on stationary trunk. Because of this
matching, perceived trunk stationariness during head rotation on the stationary trunk is independent of vestibular deterioration
(related to stimulus frequency, age, ototoxic medication, etc.). The other neck proprioceptive signal, coding head-on-trunk
rotation, is superimposed on the estimate of trunk-in-space rotation, thereby yielding a notion of head-in-space. This neck
signal remains essentially unchanged with vestibular deterioration. Generally, we hold that the transformation of the vestibular
signal from the head down to the trunk proceeds further to include the hip and the legs as well as the haptically perceived
body support surface; by this, subjects yield a notion of support kinematics in space. As a consequence, spatial orientation
is impaired by chronic vestibular deterioration only to the extent that the body support is moving in space, while it is unimpaired
(determined by proprioception alone) during body motion with respect to a stationary support.
Electronic Publication 相似文献
38.
39.
40.