全文获取类型
收费全文 | 440939篇 |
免费 | 28541篇 |
国内免费 | 2955篇 |
专业分类
耳鼻咽喉 | 5995篇 |
儿科学 | 9888篇 |
妇产科学 | 11627篇 |
基础医学 | 63257篇 |
口腔科学 | 13421篇 |
临床医学 | 35979篇 |
内科学 | 90667篇 |
皮肤病学 | 9487篇 |
神经病学 | 33058篇 |
特种医学 | 16461篇 |
外国民族医学 | 126篇 |
外科学 | 68532篇 |
综合类 | 10491篇 |
现状与发展 | 1篇 |
一般理论 | 146篇 |
预防医学 | 22323篇 |
眼科学 | 10601篇 |
药学 | 35447篇 |
1篇 | |
中国医学 | 2349篇 |
肿瘤学 | 32578篇 |
出版年
2021年 | 3624篇 |
2019年 | 3640篇 |
2018年 | 5619篇 |
2017年 | 4209篇 |
2016年 | 4419篇 |
2015年 | 5070篇 |
2014年 | 7003篇 |
2013年 | 9628篇 |
2012年 | 12928篇 |
2011年 | 13207篇 |
2010年 | 8368篇 |
2009年 | 7661篇 |
2008年 | 12185篇 |
2007年 | 13139篇 |
2006年 | 13054篇 |
2005年 | 11982篇 |
2004年 | 11512篇 |
2003年 | 11018篇 |
2002年 | 10765篇 |
2001年 | 30263篇 |
2000年 | 30858篇 |
1999年 | 25536篇 |
1998年 | 6007篇 |
1997年 | 4957篇 |
1996年 | 4439篇 |
1995年 | 4128篇 |
1994年 | 3642篇 |
1993年 | 3407篇 |
1992年 | 17436篇 |
1991年 | 16160篇 |
1990年 | 15437篇 |
1989年 | 15249篇 |
1988年 | 13641篇 |
1987年 | 13133篇 |
1986年 | 12112篇 |
1985年 | 11263篇 |
1984年 | 7587篇 |
1983年 | 6233篇 |
1982年 | 3172篇 |
1981年 | 2658篇 |
1979年 | 6096篇 |
1978年 | 3718篇 |
1977年 | 3323篇 |
1975年 | 3010篇 |
1974年 | 3469篇 |
1973年 | 3206篇 |
1972年 | 3161篇 |
1971年 | 3069篇 |
1970年 | 2758篇 |
1969年 | 2766篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
H Atlan R Sigal H Hadar R Chisin I Cohen A Lanir M Soudry Y Machtey R Schreiber J Benmair 《Journal of nuclear medicine》1986,27(2):207-215
Thirty-two patients with diversified pathology were examined with a supraconductive NMR imager using spin echo with different TR and TE to obtain T1 and T2 weighted images. They included 20 tumors (12 primary, eight metastasis), six osteomyelitis, three fractures, two osteonecrosis, and one diffuse metabolic (Gaucher) disease. In all cases except for the stress fractures, the bone pathology was clearly visualized in spite of the normal lack of signal from the compact cortical bone. Nuclear magnetic resonance (NMR) imaging proved to be at least as sensitive as radionuclide scintigraphy but much more accurate than all other imaging procedures including computed tomography (CT) and angiography to assess the extension of the lesions, especially in tumors extended to soft tissue. This is due both to easy acquisition of sagittal and coronal sections and to different patterns of pathologic modifications of T1 and T2 which are beginning to be defined. It is hoped that more experience in clinical use of these patterns will help to discriminate between tumor extension and soft-tissue edema. We conclude that while radionuclide scintigraphy will probably remain the most sensitive and easy to perform screening test for bone pathology, NMR imaging, among noninvasive diagnostic procedures, appears to be at least as specific as CT. In addition, where the extension of the lesions is concerned, NMR imaging is much more informative than CT. In pathology of the spine, the easy visualization of the spinal cord should decrease the need for myelography. 相似文献
53.
C Peabody J Van Norman L Hollister D Warner 《Progress in neuro-psychopharmacology & biological psychiatry》1991,15(1):63-70
1. Twenty-two patients hospitalized for treatment of depression were treated under conditions simulating those of home treatment. 2. Full doses of nortriptyline, from 100 to 150 mg/day, were started after baseline observations were made. 3. Two patients were dropped from the study, one for orthostatic hypotension, one for an aberrant response to nortriptyline. Two additional patients developed orthostasis which was easily managed. Otherwise no unusual side effects were noted. 4. After six days of treatment, 9 of 20 patients showed significant improvement with an overall reduction in scores on the Hamilton Depression Scale of 49% for the entire group. 5. Using the weight-adjusted dosage schedule, 18 of the 21 patients attained plasma concentrations of nortriptyline within the presumed therapeutic range; however, no clear relationship could be established between plasma concentrations and clinical response. 6. With proper selection of patients, it should be possible to treat at home some patients who currently are considered to require hospitalization. 相似文献
54.
We studied two patients which showed a paralysis of the oculomotor nerve on one side and isolated paralysis of the superior rectus on the other side. On the side of oculomotor nerve paralysis, midbrain infarct extending from the paramedian tegmentum to crus cerebri was demonstrated in one case who showed no recovery, and a small lacuna in midbrain tegmentum in another one who showed complete recovery. On the side of isolated paralysis of the superior rectus, no lesion was demonstrated by CT and MRI, and no clinical signs of the involvement of fiber tracts or nuclei were evident in both cases. A unilateral lesion of oculomotor nerve nucleus caused a paralysis of the contralateral superior rectus. 相似文献
55.
P F Rogers G A Head Y K Lungershausen P R Howe 《Journal of the autonomic nervous system》1991,34(1):9-16
The potential role of adrenaline, both circulating and in the central nervous system, in the maintenance of high blood pressure was examined in stroke-prone spontaneously hypertensive rats (SHRSP). alpha-Monofluoromethyldopa, a long-lasting inhibitor of dopa decarboxylase, was used to induce rapid depletion of central and peripheral catecholamine stores. Subsequent inhibition of phenylethanolamine-N-methyltransferase (PNMT) allowed the gradual restoration of dopamine and noradrenaline but not adrenaline, resulting in a greater relative depletion of adrenaline. Adrenaline was almost totally depleted in the circulation and peripheral tissues. The resting level of blood pressure, however, was unaffected, excepting after administration of a vasopressin (AVP) antagonist. Moreover, there was no reduction in the magnitude of acute pressor responses to electrical stimulation of the rostral ventrolateral medulla oblongata (C1 area), despite extensive loss of adrenaline from the brainstem and spinal cord. The results suggest that adrenaline contributes to the resting level of blood pressure but that its loss can be offset by the pressor activity of AVP. Thus neither central nor peripheral adrenaline stores appear to be essential for the maintenance of hypertension or for centrally-evoked vasoconstriction in adult SHRSP. 相似文献
56.
M K Song W Y Shin N F Adham N V Costea 《The American journal of clinical nutrition》1989,49(4):701-707
The effects of different amounts of dietary zinc on the Zn absorption rate and on Zn, calcium and magnesium concentrations in tissues of MOPC 104E tumor-bearing Balb/c mice were determined. The Zn absorption rate was inversely related to the amounts of Zn in their diets and was lower than that of nontumor-bearing control mice fed a laboratory mice chow. Zn concentrations of tumor-bearing mice were also low compared with control mice but tumor Zn concentrations, regardless of the concentrations of Zn in the diets, were higher than those of normal tissues of the host other than the pancreas. Ca concentrations in tumor and tissues of tumor-bearing mice were higher than in control animals but Mg concentrations in tissues of tumor-bearing mice appeared to be similar to those of control mice. Results suggest that tumor-bearing mice have a lower intestinal Zn absorption capacity and a higher Zn uptake rate causing other tissues to become hypozincemic and hypercalcemic. 相似文献
57.
The contractile response of isolated guinea pigs common bile ducts (CBD) to transmural electrical stimulation and the effects of morphine and naloxone was studied. Contractile responses increased as a function of stimulus frequency. In the absence of naloxone morphine inhibited the contractile response to electrical stimulation in a dose-dependent manner. Naloxone prevented the inhibitory effect of morphine on the contractile response to electrical stimulation. We conclude that smooth muscle of the CBD in guinea pig is functional and can contribute to biliary motility, and that opiate receptors exist in nerve elements in the CBD. 相似文献
58.
59.
Geert Verreck Annelies Decorte Koen Heymans Jef Adriaensen Dirk Cleeren Adri Jacobs Dehua Liu David Tomasko Albertina Arien Jef Peeters Patrick Rombaut Guy Van den Mooter Marcus E Brewster 《European journal of pharmaceutical sciences》2005,26(3-4):349-358
The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency. 相似文献
60.
M Yoshino Y Sakaguchi N Kuriya Y Ohtani F Yamashita T Hashimoto K Oyanagi K Tada K Narisawa T Kitagawa 《Neuropediatrics》1991,22(4):198-202
A nationwide survey of transient hyperammonemia in newborns was carried out in Japan. A total of 18 patients, consisting of 12 male and 6 female infants, were reported from 11 facilities. These neonates exhibited hyperammonemia with plasma ammonia levels in the range from 124 to 6256 micrograms/dl. Four newborn infants of the 18 died in the neonatal period, and an additional one died in the early infancy. Among the 13 infants who were alive at the time of this survey, 6 had neurological sequelae, including mental retardation, spastic quadriplegia and epilepsy. The multivariate analysis revealed that the Apgar score at 1 minute, peak plasma ammonia concentration, birth weight and sex were significant factors affecting the prognosis of life. 相似文献