全文获取类型
收费全文 | 43546篇 |
免费 | 2986篇 |
国内免费 | 853篇 |
专业分类
耳鼻咽喉 | 236篇 |
儿科学 | 1755篇 |
妇产科学 | 1162篇 |
基础医学 | 5950篇 |
口腔科学 | 1229篇 |
临床医学 | 2940篇 |
内科学 | 8842篇 |
皮肤病学 | 689篇 |
神经病学 | 3256篇 |
特种医学 | 1975篇 |
外国民族医学 | 4篇 |
外科学 | 5880篇 |
综合类 | 2865篇 |
现状与发展 | 3篇 |
预防医学 | 2969篇 |
眼科学 | 423篇 |
药学 | 3876篇 |
27篇 | |
中国医学 | 1228篇 |
肿瘤学 | 2076篇 |
出版年
2024年 | 94篇 |
2023年 | 610篇 |
2022年 | 1406篇 |
2021年 | 1856篇 |
2020年 | 1509篇 |
2019年 | 2512篇 |
2018年 | 2457篇 |
2017年 | 1635篇 |
2016年 | 1218篇 |
2015年 | 1257篇 |
2014年 | 2120篇 |
2013年 | 2177篇 |
2012年 | 1509篇 |
2011年 | 1644篇 |
2010年 | 1304篇 |
2009年 | 1432篇 |
2008年 | 1289篇 |
2007年 | 1180篇 |
2006年 | 1114篇 |
2005年 | 901篇 |
2004年 | 811篇 |
2003年 | 806篇 |
2002年 | 589篇 |
2001年 | 549篇 |
2000年 | 520篇 |
1999年 | 487篇 |
1998年 | 373篇 |
1997年 | 338篇 |
1996年 | 291篇 |
1995年 | 228篇 |
1994年 | 200篇 |
1993年 | 140篇 |
1992年 | 120篇 |
1991年 | 129篇 |
1990年 | 104篇 |
1989年 | 107篇 |
1988年 | 100篇 |
1985年 | 1007篇 |
1984年 | 1794篇 |
1983年 | 1101篇 |
1982年 | 1229篇 |
1981年 | 1191篇 |
1980年 | 984篇 |
1979年 | 880篇 |
1978年 | 800篇 |
1977年 | 684篇 |
1976年 | 789篇 |
1975年 | 558篇 |
1974年 | 496篇 |
1973年 | 552篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
《Journal of Clinical Orthopaedics and Trauma》2019,10(2):380-386
Additive manufacturing is a rapidly emerging technology which is being successfully implemented in the various field of medicine as well as in orthopaedics, where it has applications in reducing cartilage defects and treatments of bones. The technology helps through systematic collection of information about the shape of the "defects" and precise fabrication of complex 3D constructs such as cartilage, heart valve, trachea, myocardial bone tissue and blood vessels. In this paper, a large number of the relevant research papers on the additive manufacturing and its application in medical specifically orthopaedics are identified through Scopus had been studied using Bibliometric analysis and application analysis is undertaken. The bibliometric analysis shows that there is an increasing trend in the research reports on additive manufacturing applications in the field of orthopaedics. Discussions are on using technological advancement like scanning techniques and various challenges of the orthopaedic being met by additive manufacturing technology. For patient-specific orthopaedic applications, these techniques incorporate clinical practice and use for effective planning. 3D printed models printed by this technology are accepted for orthopaedic surgery such as revision of lumbar discectomy, pelvic surgery and large scapular osteochondroma. The applications of additive manufacturing in orthopaedics will experience a rapid translation in future. An orthopaedic surgeon can convert need/idea into a reality by using computer-aided design (CAD) software, analysis software to facilitate the manufacturing. Thus, AM provides a comprehensive opportunity to manufacture orthopaedic implantable medical devices. 相似文献
3.
A method is presented for 3D MRI in an extended field of view (FOV) based on continuous motion of the patient table and an efficient acquisition scheme. A gradient-echo MR pulse sequence is applied with lateral (left-right (L/R)) frequency-encoding direction and slab selection along the direction of motion. Compensation for the table motion is achieved by a combination of slab tracking and data alignment in hybrid space. The method allows fast k-space coverage to be achieved, especially when a short sampling FOV is chosen along the direction of table motion, as is desirable for good image quality. The method can be incorporated into different acquisitions schemes, including segmented k-space scanning, which allows for contrast variation with the use of magnetization preparation. Head-to-toe images of volunteers were obtained with good quality using 3D spoiled gradient-echo sequences. As an example of magnetization-prepared imaging, fat/water separated images were acquired using chemical shift selective (CHESS) presaturation pulses. 相似文献
4.
Introduction The associations between vitamin D receptor (VDR) Bsm I and Fok I genotypes, parity, and risk of osteoporotic hip fracture were evaluated in a statewide population-based case-control study in Utah.Methods Women age 50–89 years with hip fracture (n=882) were ascertained via surveillance of 18 Utah hospitals from 1997 to 2001. Age-matched controls were randomly selected (n=897). Participants were interviewed in their homes, and blood samples were collected for genotyping.Results In logistic regression analyses that controlled for multiple confounders, Bsm I VDR genotype but not Fok I genotype was associated with risk of osteoporotic hip fracture (OR bb vs. BB genotype: 0.68; 95% CI: 0.50, 0.95). In similar analyses, no overall association was observed between parity status and risk of osteoporotic hip fracture. However, the effect of VDR genotype was modified by parity status. Among nulliparous women (n=140), Bsm I genotype was not associated with risk of hip fracture (OR bb vs. BB: 0.82; 95% CI: 0.28, 2.4); among primiparous women (n=133), bb genotype was associated with increased risk of hip fracture (OR bb vs. BB: 3.30; 95% CI: 0.96, 11.29); among multiparous women (n=1,400), bb genotype was associated with decreased risk of hip fracture (OR bb vs. BB: 0.59; 95% CI: 0.42, 0.84).Conclusion VDR Bsm I genotype was associated with risk of hip fracture in Utah women, and this effect was modified by parity status. Hormonal or lifestyle factors related to parity may underlie this interaction. 相似文献
5.
W. Nörenberg Ernst Schöffel Bela Szabo Klaus Starke 《Naunyn-Schmiedeberg's archives of pharmacology》1997,356(2):159-165
The aim of the study was to subclassify the soma-dendritic α2-autoreceptors in the locus coeruleus (LC) of the rat by means of antagonists. To this end, the frequency of spontaneous action
potentials was recorded extracellularly from single LC neurones in brain slices. The neurones fired spontaneously at an average
rate of 1 Hz. The selective α2-adrenoceptor agonist 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14,304) and noradrenaline decreased the action potential
discharge with IC50 values of 5 and 510 nM, respectively. The concentration-inhibition curves of UK 14,304 and noradrenaline were shifted to the
right by phentolamine (0.15 μM) and rauwolscine (0.15 μM) but not by prazosin (1 μM). Apparent K
d values of phentolamine were 17 nM (against UK 14,304) and 20 nM (against noradrenaline). Apparent K
d values of rauwolscine were 47 nM (against UK 14,304) and 70 nM (against noradrenaline). (+)-Oxaprotiline (1 μM) suppressed
the firing of the neurones within 10 to 33 min. In the continued presence of oxaprotiline, phentolamine and rauwolscine restored
firing with EC50 values of 120 and 250 nM, respectively. Prazosin (1 μM) again was ineffective. All three antagonist affinity estimates –
against UK 14,304, exogenous noradrenaline and endogenous noradrenaline (that accumulates in the extracellular space in the
presence of oxaprotiline) – yield an affinity order phentolamine > rauwolscine >> prazosin, prazosin being ineffective even
at a concentration of 1 μM. These findings identify the soma-dendritic α2-autoreceptors of the LC as the rat variant of the α2A/D-adrenoceptor, i.e. α2D. Not only presynaptic but also soma-dendritic α2-autoreceptors may at least predominantly be α2A/D throughout the nervous system.
Received: 3 March 1997 / Accepted: 21 April 1997 相似文献
6.
S B Wieslander B T Mortensen L Binderup N I Nissen 《European journal of haematology》1987,39(1):35-38
10 patients with CLL and 2 with CML were treated with gradually increasing doses of 1 alpha(OH)D3, up to 4 micrograms daily during 6 wk. 3 patients with preleukemia and 1 with myelofibrosis were treated with 2 micrograms daily of 1 alpha(OH)D3 for a prolonged period up to 17 wk. The treatment with 1 alpha (OH)D3 did not result in changes of disease parameters in any of the patients under study. Receptor studies for 1,25(OH)2D3 were performed in 8 CLL patients and revealed only 1 patient with increased specific receptor binding capacity. The maximum tolerable dose of 1 alpha(OH)D3 varied individually, but was in the range of 2-4 micrograms daily. 相似文献
7.
Bodo Lehmann 《Experimental dermatology》2009,18(2):97-108
Abstract: Irradiation of human keratinocytes with UVB (280–320 nm) in vitro and in vivo activates the metabolism of 7‐dehydrocholesterol to hormonally active calcitriol. The production of calcitriol in the skin strongly depends on the photosynthesis of vitamin D3 which is biologically inactive in the first instance. Vitamin D3 serves as the starting substrate for two subsequent enzymatic hydroxylation steps in epidermal keratinocytes. Both the amount of vitamin D3 and the activity of anabolic and catabolic vitamin D hydroxylases determine the cutaneous level of calcitriol. The hormonally active metabolite of vitamin D3 regulates a huge number of genes in keratinocytes, and thus acts in an autocrine and/or paracrine manner. This local pathway of vitamin D3 is unique, but its relevance for healthy and diseased skin is widely unknown, yet. Experimental findings implicate several questions: ( 1 ) Is UVB‐induced formation of calcitriol involved in regulation of growth and differentaition of epidermal cells as well as immunological and skin protective processes? ( 2 ) What endogenous and exogenous factors including drugs affect the cutaneous vitamin D3 pathway? From a therapeutical point of view, it has been known for a long time that topical application of calcitriol and its analogs can improve hyperproliferative skin diseases like psoriasis. In spite of many encouraging studies in recent years, the fields of the routinely therapeutical application of calcitriol or vitamin D analogs in dermatology (e.g. treatment of immunological, inflammatory, malignancies and infectious skin diseases) have not been intensified. Why is that? 相似文献
8.
蛋白质组学是研究细胞内所有蛋白质及其动态变化规律的科学,近年来它被广泛应用于生命科学的各个领域.二维聚丙烯酰胺凝胶电泳法(2D PAGE)是蛋白质组学核心技术.就蛋白质组学在皮肤病学基础研究和临床皮肤病中的应用进行综述. 相似文献
9.
R. San Juan M. Yebra C. Lumbreras F. López-Medrano M. Lizasoain J.C. Meneu J. Delgado A. Andrés J.M. Aguado 《Clinical transplantation》2009,23(5):666-671
Abstract: Long-term prophylaxis against cytomegalovirus (CMV) started immediately after transplantation in (D+/R−) poses a higher risk of late-onset CMV disease. Delayed CMV prophylaxis could allow a transitory exposure of the immune system to CMV, which would let the immune system mount an adequate CMV-specific cytotoxic response in (D+/R−) patients and confer protection against CMV disease. We included all (D+/R−) solid organ transplant recipients (SOT) performed at our institution (January 3/October 6) who received CMV prophylaxis (mainly with oral valganciclovir) during 100 d. In the first period (until December 4), prophylaxis was initiated immediately after transplantation (conventional prophylaxis: CP). Since January 5, it was initiated after 14 d (delayed prophylaxis: DP). Incidence and severity of CMV disease was compared between both groups. A total of 44 SOT recipients were included (CP: 26 and DP: 18). CMV disease was diagnosed in eight patients (18%), seven of 26 (27%) in the CP group, and one of 18 (5.5%) in the DP group (p = 0.07). CMV colitis was reported in five of 26 patients in the CP group (19%), whereas there were no cases of visceral CMV disease in the DP group (p = 0.048). A 14-d delay in the beginning of long-term prophylaxis against CMV in (D+/R−) is safe and could prevent the onset of late-CMV disease. 相似文献
10.
C. COLETTE M. C. GOUTTEBEL† L. H. MONNIER B. SAINT-AUBERT† H. JOYEUX† 《European journal of clinical investigation》1986,16(4):271-276
Seventeen patients who had undergone extensive small bowel resection were studied for calcium absorption (FACa) and plasma vitamin D metabolites. FACa was measured by a double radio-tracer technique and expressed as percentage of total oral dose. FACa was decreased compared with controls (34%, range: 3-46 v 65%, range: 57-73, P less than 0.01). A positive correlation (r = 0.49, P = 0.05) was found between FACa and the remaining length of small bowel (SBL). As wide variations in both SBL and duration after surgery were observed among the seventeen investigated patients, we were led to individualize less heterogeneous subgroups of patients. Better correlations were found when the patients were divided into two subgroups according to whether the time interval between the resection and the investigation was shorter (r = 0.75, n = 11, P less than 0.02) or longer (r = 0.89, n = 6, P = 0.05) than 2 years. In thirteen patients who had a SBL shorter than 100 cm, a positive correlation was observed between FACa and the time interval after surgery (months): r = 0.65, P less than 0.05. Plasma 1,25 (OH)2D was markedly reduced in the whole group (31 pmol l-1, range: 8-108) compared with controls (103 pmol-1, range: 59-134, P less than 0.01). The present study shows that in extensively small bowel resected patients, calcium absorption is reduced, the alteration being dependent both on the length of the remnant small bowel and on the time after surgery.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献