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排序方式: 共有712条查询结果,搜索用时 31 毫秒
1.
Resetting of the arterial baroreflex increases orthostatic sympathetic activation and prevents postural hypotension in rabbits 总被引:1,自引:1,他引:0
Atsunori Kamiya Toru Kawada Kenta Yamamoto Daisaku Michikami Hideto Ariumi Kazunori Uemura Can Zheng Syuji Shimizu Takeshi Aiba Tadayoshi Miyamoto Masaru Sugimachi Kenji Sunagawa 《The Journal of physiology》2005,566(1):237-246
Since humans are under ceaseless orthostatic stress, the mechanism to maintain arterial pressure (AP) under orthostatic stress against gravitational fluid shift is of great importance. We hypothesized that (1) orthostatic stress resets the arterial baroreflex control of sympathetic nerve activity (SNA) to a higher SNA, and (2) resetting of the arterial baroreflex contributes to preventing postural hypotension. Renal SNA and AP were recorded in eight anaesthetized, vagotomized and aortic-denervated rabbits. Isolated intracarotid sinus pressure (CSP) was increased stepwise from 40 to 160 mmHg with increments of 20 mmHg (60 s for each CSP level) while the animal was placed supine and at 60 deg upright tilt. Upright tilt shifted the CSP–SNA relationship (the baroreflex neural arc) to a higher SNA, shifted the SNA–AP relationship (the baroreflex peripheral arc) to a lower AP, and consequently moved the operating point to marked high SNA while maintaining AP. A simulation study suggests that resetting in the neural arc would double the orthostatic activation of SNA and increase the operating AP in upright tilt by 10 mmHg, compared with the absence of resetting. In addition, upright tilt did not change the CSP–AP relationship (the baroreflex total arc). A simulation study suggests that although a downward shift of the peripheral arc could shift the total arc downward, resetting in the neural arc would compensate this fall and prevent the total arc from shifting downward to a lower AP. In conclusion, upright tilt increases SNA by resetting the baroreflex neural arc. This resetting may compensate for the reduced pressor responses to SNA in the peripheral cardiovascular system and contribute to preventing postural hypotension. 相似文献
2.
Yoshitaka Hirooka Yoshikuni Kimura Masatsugu Nozoe Yoji Sagara Koji Ito Kenji Sunagawa 《Hypertension research》2006,29(1):49-56
Amlodipine is a dihydropyridine calcium channel blocker that is widely used for the treatment of hypertensive patients and has an antioxidant effect on vessels in vitro. The aim of the present study was to examine whether treatment with amlodipine reduced oxidative stress in the brains of stroke-prone spontaneously hypertensive rats (SHRSP). The animals received amlodipine, nicardipine or hydralazine for 30 days in their drinking water. Levels of thiobarbituric acid-reactive substances (TBARS) in the brain (cortex, cerebellum, hypothalamus, and brainstem) were measured before and after each treatment. Systolic blood pressure decreased to similar levels in the amlodipine-, nicardipine-, and hydralazine-treated groups. Urinary norepinephrine excretion was significantly reduced in SHRSP after treatment with amlodipine, but not with nicardipine or hydralazine. Levels of TBARS in the cortex, cerebellum, hypothalamus, and brainstem were significantly higher in SHRSP than in Wistar-Kyoto rats (WKY), and were reduced in amlodipine-treated, but not in nicardipine- or hydralazine-treated, SHRSP. Electron spin resonance spectroscopy revealed increased levels of reactive oxygen species in the brains of SHRSP, which were reduced by treatment with amlodipine. Intracisternal infusion of amlodipine also reduced systolic blood pressure, urinary norepinephrine excretion, and the levels of TBARS in the brain. These results suggested that oxidative stress in the brain was enhanced in SHRSP compared with WKY rats. In addition, antihypertensive treatment with amlodipine reduced oxidative stress in all areas of the brain examined and decreased blood pressure without a reflex increase in sympathetic nerve activity in SHRSP. 相似文献
3.
Tamaki Sasaki Tetsuya Sato Yoshiyuki Jyo Nobuya Tanda Hitoshi Tamai Gengo Osawa 《Clinical and experimental nephrology》1997,1(1):32-40
Background We previously found that glomerular epithelial cells play an important role in the formation of adhesive lesions. Glomerular
sclerotic lesions develop after the inital adhesive lesions.
Methods Two series of experiments were done with spontaneously diabetic WBN/Kob rats. These rats develop segmental glomerular sclerotic
lesions with aging. The first series of experiments was intended to clarify the kinetics of glomerular cells on progressive
glomerular damage in these rats. The second series of experiments was designed to study the relationship between proliferation
(judged by % bromodeoxyuridine-positive cells) of glomerlar epithelial cells and sclerotic lesions with adhesions.
Results In the first series, rats having increased proteinuria showed segmental glomerular sclerotic lesions with adhesions. At the
same time, increased labeling indices of tuft cells and epithelial cells of Bowman's capsule were observed. In the second
series, no significant increase in the labeling indices of tuft cells with sclerotic lesions was observed, compared to tuft
cells without sclerotic lesions. In sclerotic lesions with adhesion, bromodeoxyurdine-positive cells were observed that were
not distinguishable as podocytes or epithelial cells of Bowman's capsule. The highest labelling index was noted in the epithelial
cells of Bowman's capsules with sclerosis.
Conclusion This study shows that the proliferation of glomerular epithelial cells (mainly epithelial cells of Bowman's capsule) occurs
in glomerular sclerotic lesions with adhesions. 相似文献
4.
To examine the myocardial contractile response of the diabetic heart, effects of isoproterenol (ISO) and norepinephrine (NE) on perfused hearts isolated from streptozotocin (STZ)-induced diabetic rats and insulin-treated diabetic rats were evaluated. Male Sprague-Dawley rats, weighing 200-260 g, were divided into the control (C)-group, diabetes mellitus (DM)-group and diabetes mellitus treated with insulin (DMI)-group. The C group was injected with buffered vehicle. DM and DMI groups were injected intravenously with 60 mg/kg STZ on the first day. Three days after STZ injection, the DMI group was subsequently treated with 4 U of Lente insulin subcutaneously every day. At 45 days after injection of STZ, experiments were performed using a Langendorff perfused heart preparation. The heart was paced at 300 beats/min, and myocardial developed tension (T) was measured isometrically. Plasma glucose values (mg/dl) were 142.4 +/- 8.7 in C, 499.3 +/- 15.6 in DM and 370.6 +/- 27.6 in DMI group. The order of percent increase in T induced by ISO (3 X 10(-9) - 3 X 10(-8) g) was C = DMI much greater than DM, and that by NE (10(-7) - 10(-6) g) was C greater than DMI greater than DM. On the other hand, the percent increase in T induced by CaCl2 (1.1 X 10(-4) - 2.2 X 10(-3) g) and aminophylline (AMI, 0.31 X 10(-3) - 5.00 X 10(-3) g) was not significantly different among three groups. These results indicate that adrenergic receptor-mediated contractile response was significantly depressed in the diabetic heart. 相似文献
5.
Ryoji Kajiwara Takahiro Matsuno Osamu Ishida Toru Sunagawa Osami Suzuki Mitsuo Ochi 《Nordisk plastikkirurgisk forening [and] Nordisk klubb for handkirurgi》2004,38(6):373-375
We report a case of an anterior interosseous nerve palsy after closed reduction and percutaneous pinning of open fractures of the radius and ulna in an adult. Operative findings showed that the anterior interosseous nerve was trapped between the distal and proximal part of the fractured radius. Treatment by neurorrhaphy gave a satisfactory result. 相似文献
6.
H Ando H Yasui H Kado K Yonenaga T Shin H Iwao H Sunagawa S Honda 《[Zasshi] [Journal]. Nihon Kyōbu Geka Gakkai》1990,38(4):618-624
From October, 1980, to June, 1987, thirty-eight infants less than one year old underwent correction for total anomalous pulmonary venous connection (TAPVC). Overall operative mortality and late mortality were 13% and 6%, respectively. Residual pulmonary hypertension was noted in 4 patients: three had pulmonary venous obstruction at the site of atrial anastomosis (PVOA) and one had supracardiac (Ia) lesion left after repair of mixed type (IV: Ia + III) of TAPVC. Two late deaths occurred in these with PVOA. Twenty-two patients with supracardiac (I) or infracardiac (III) TAPVC were divided into three groups according to the technical development in atrial anastomosis: the large anastomosis in which venous incision reached into at least one pulmonary vein beyond common pulmonary vein and the continuous running suture were used in 10 patients (group 1), the appropriate size of anastomosis in which venous incision limited within the common pulmonary vein and the continuous running suture used in 4 patients (group 2), and the appropriate size of anastomosis and the interrupted suture in 8 patients (group 3). PVOA were 3 (33%) in group 1, but 0 (0%) in group 2 and 3. Two late death occurred all in group 1 with PVOA. Cardiopulmonary bypass time and aortic clamp time in group 3 were 91 min and 74 min respectively, which did not become longer than those in both group 1 and group 2. Interrupted suture technique does not make operating time longer than continuous running suture one. PVOA is one of the important factors predicting late operative result.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
N Bowling V L Wyss P J Gengo B Utterback R F Kauffman J S Hayes 《European journal of pharmacology》1990,187(2):155-164
Effects of prolonged isoproterenol infusion upon the density of cardiac calcium channels, calcium-mediated contractile responses, and the ability of forskolin to enhance tension development and cyclic AMP accumulation were studied in ventricular muscle preparations from Sprague-Dawley rats. Isoproterenol infusion (400 micrograms/kg per h s.c., 4 days) significantly decreased calcium channel density (Bmax) in cardiac microsomal membranes as quantified by a 32% decrease in specific [3H]nitrendipine binding sites; binding affinity (KD) was unchanged. A 57% decrease of beta-adrenoceptors confirmed homologous down regulation. To examine functional effects of decreased [3H]nitrendipine binding sites, responses to calcium, BAY K8644 and nifedipine were determined in isolated right ventricular strips. Significant decreases in basal developed tension were observed in muscles from isoproterenol-infused rats. However, concentration-dependent increases in contractility in response to CaCl2 or BAY K8644 were comparable, and the negative inotropic effect of nifedipine was unchanged. Whereas isoproterenol infusion was associated with significantly decreased basal cardiac cyclic AMP concentrations, exposure of ventricular strips from either vehicle- or isoproterenol-infused rats to 10 microM forskolin resulted in comparable increases in cyclic AMP and in developed tension. Cumulative, submaximal concentrations of forskolin also produced similar increases in contractility with maximum responses in ventricular strips from vehicle-infused animals attained at 4.4 microM forskolin. Higher concentrations resulted in automaticity. By contrast, ventricle from isoproterenol-infused animals responded to 14.4 microM forskolin with maximal increases in force of contraction. 相似文献
8.
A series of 1 beta-methylcarbapenem compounds, which have a 5'-substituted-N-methylpyrrolidin-3'-ylthio group as a C-2 side chain, have been prepared and their biological properties were investigated. Substitution with a methyl group on the nitrogen atom in the C-2 side chain effectively enhanced stability to renal dehydropeptidase-I as well as introduction of methylene spacer between the aminocarbonyl group and the pyrrolidine ring of the 5'-aminocarbonylpyrrolidin-3'-ylthio group. 相似文献
9.
Tadashi Nomura MD ; Hiroto Terashi MD PhD ; Makoto Omori MD ; Atsushi Sakurai MD ; Takeru Sunagawa PhD ; Masumi Hasegawa MS ; Shinya Tahara MD PhD 《Wound repair and regeneration》2007,15(6):833-837
Hypertrophic scars (HS) are a consequence of abnormal wound healing. We examined fatty acids that are contained within, and participate in, every reaction through the membrane; then, we analyzed the percentage composition of the fatty acids in deepithelialized normal dermis (ND) and HS. In vivo HS samples were obtained from six patients undergoing surgical excision, and ND samples from five patients undergoing skin grafting surgery for excess. In vitro, cultured fibroblasts from HS and ND were also analyzed. The percentage composition of fatty acids extracted from all the samples was analyzed. In vivo, arachidonic acid (20:4) was significantly more abundant in HS than in ND, in the phospholipids from both whole tissue and cell membranes. In vitro, there were no significant differences among ND, HS, and 10% fetal calf serum. The results suggest that HS formation does not necessarily involve simple excess of 20:4; however, there are considerable differences in the percentage composition of 20:4 between ND and HS. Arachidonic acid probably participates in the formation and maintenance of HS, whereas in vitro cultured fibroblasts are affected largely by fetal calf serum. 相似文献
10.
Yoshio Kasuga MD Akira Sugenoya Shinya Kobayashi Gengo Kaneko Hiroyuki Masuda Minoru Fujimori Shozo Takahashi Futoshi Iida 《Surgery today》1990,20(3):283-289
The purpose of this study was to evaluate the acute effects of corticosteroid and iodide preoperative therapy in patients
with Graves' disease in terms of thyroid function and immunological parameters. The above combination was prescribed for 4
patients who had experienced severe side effects from antithyroid drugs (ATD) in order to reduce the possibility of post-thyroidectomy
thyroid storm. Corticosteroids were employed daily for four days, and iodides were given daily for two weeks prior to thyroidectomy.
The free T3 values decreased rapidly to euthyroid levels following the administration of both drugs, although the free T4 values were still much higher than normal in 3 of the 4 patients at the time of surgery. By comparison, 3 of 8 patients treated
with ATD also had thyroid hormone levels above normal. Studies of lymphocyte subsets revealed that the percentage of helper
T cells was significantly less in the corticosteroidiodide treatment group than in the control and ATD groups. It is thus
possible that postoperative thyroid storm might be prevented through corticosteroid-iodide therapy by virtue of the reduction
of free T3 values to within the normal range by the time of surgery. The acute suppression of helper T cells was another result of this
form of therapy observed. 相似文献