全文获取类型
收费全文 | 517965篇 |
免费 | 37493篇 |
国内免费 | 11192篇 |
专业分类
耳鼻咽喉 | 6242篇 |
儿科学 | 9903篇 |
妇产科学 | 11556篇 |
基础医学 | 73846篇 |
口腔科学 | 14144篇 |
临床医学 | 46969篇 |
内科学 | 97441篇 |
皮肤病学 | 10018篇 |
神经病学 | 33896篇 |
特种医学 | 18647篇 |
外国民族医学 | 147篇 |
外科学 | 73620篇 |
综合类 | 33049篇 |
现状与发展 | 30篇 |
一般理论 | 76篇 |
预防医学 | 27319篇 |
眼科学 | 12795篇 |
药学 | 47210篇 |
123篇 | |
中国医学 | 9967篇 |
肿瘤学 | 39652篇 |
出版年
2023年 | 2887篇 |
2022年 | 6898篇 |
2021年 | 9784篇 |
2020年 | 6897篇 |
2019年 | 7373篇 |
2018年 | 9335篇 |
2017年 | 7893篇 |
2016年 | 7752篇 |
2015年 | 10206篇 |
2014年 | 13301篇 |
2013年 | 14781篇 |
2012年 | 20373篇 |
2011年 | 21215篇 |
2010年 | 13971篇 |
2009年 | 12121篇 |
2008年 | 16927篇 |
2007年 | 17752篇 |
2006年 | 17013篇 |
2005年 | 15477篇 |
2004年 | 13578篇 |
2003年 | 13252篇 |
2002年 | 12183篇 |
2001年 | 31306篇 |
2000年 | 31348篇 |
1999年 | 25991篇 |
1998年 | 6718篇 |
1997年 | 5974篇 |
1996年 | 5046篇 |
1995年 | 4641篇 |
1994年 | 4161篇 |
1993年 | 3576篇 |
1992年 | 16896篇 |
1991年 | 15580篇 |
1990年 | 14853篇 |
1989年 | 14594篇 |
1988年 | 13141篇 |
1987年 | 12521篇 |
1986年 | 11539篇 |
1985年 | 10689篇 |
1984年 | 7233篇 |
1983年 | 5862篇 |
1982年 | 2963篇 |
1979年 | 5650篇 |
1978年 | 3529篇 |
1977年 | 3172篇 |
1975年 | 2755篇 |
1974年 | 3216篇 |
1973年 | 2992篇 |
1972年 | 2931篇 |
1971年 | 2895篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
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
83.
目的:在原核系统中表达并纯化大肠杆菌胞嘧啶脱氨酶(cytosine deaminase,CD),制备鼠抗大肠杆菌CD多克隆抗体,方法:亚克隆CD基因到原核表达载体pMAL-c2和pBV222中,并转化入大肠杆菌DH5α内,诱导表达并纯化MBP-CD和6his-CD融合蛋白,用纯化的MBP-CD融合蛋白免疫小鼠制备多克隆抗体。结果:通过重组质粒的酶切筛选出重组阳性克隆,成功地表达和纯化出MBP-CD和6his-CD融合蛋白,用纯化的MBP-CD成功制备了鼠抗CD多克隆抗体,并用6his-CD和GST-CD重组蛋白进行Western印迹分析,证实了抗体的正确性,结论:应用多克隆抗体可以检测体内外CD基因的表达,为临床前和临床上深入开展CD基因的生物治疗研究提供重要的实验材料。 相似文献
84.
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
85.
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
86.
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
87.
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
88.
89.
目的探讨儿童过敏性紫癜的影像学特点及其临床价值。方法回顾性分析32例过敏性紫癜并发肠套叠患儿的临床及影像学资料。结果出现并发症之前过敏性紫癜的腹部X线主要表现为局限性小肠充气扩张,粘膜增粗,肠间隙增宽,可伴有液平;B超显示为不同程度的多发节段性肠壁水肿增厚,肠管狭窄等表现;出现并发症后,其X线表现加重,部分病例伴有肠穿孔;B超及X线监视下空气灌肠可以明确是否并发肠套叠,部分病例可通过空气灌肠达到复位治疗的目的。结论影像学检查的重要临床价值在于能与需要手术治疗的其他急腹症相鉴别,同时可以了解其是否并发常见的并发症,为临床确定治疗方案提供可靠的信息。 相似文献
90.